As the title says, I want to use ArnoPro as my main font for text while using MinionPro for all math (inline or display).
What I did for ArnoPro was since I have Windows on my laptop as well as Linux Mint (which is what I'm using now and for LaTeX), I followed the instructions here and installed the Arno Pro fonts from my Windows Adobe into Linux. I now have the following as my minimal example (I hope it is minimal enough); note the HUGE preamble:
\documentclass[12pt]{article}
\usepackage{bigints}
\usepackage{microtype}
\usepackage[textlf,mathlf,minionint]{MinionPro}
% If I want to use MinionPro instead of ArnoPro,
% I simply comment out all packages below this.
%\DeclareSymbolFont{missing}{OML}{cmr}{m}{n}
%\DeclareMathSymbol{\ell}{\mathord}{missing}{'140}
%\usepackage[]{mathspec}
%\defaultfontfeatures{Ligatures={TeX}}
%\setmathsfont(Digits,Latin,Greek)[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic,
%Numbers={Proportional}]{ArnoPro}
%\setmathrm
%[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{ArnoPro}
%\setmathsf
%[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{ArnoPro}
%\setmathtt
%[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{ArnoPro}
%\setmathcal
%[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{ArnoPro}
%\setmathbb
%[UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{ArnoPro}
%\RequirePackage{xltxtra,xunicode}
%\defaultfontfeatures{Mapping=tex-text, Numbers=OldStyle}
%\aliasfontfeatureoption{Ligatures}{Historic}{Historical}
%\setromanfont
%[Mapping=tex-text,
%Ligatures={Common},
%Numbers=OldStyle,
%SizeFeatures={%
% {Size={-10}, Font=*Caption},
% {Size={10-13.0}, Font=*},
% {Size={13.01-19.9}, Font=*Subhead, Ligatures=Rare, Contextuals={Swash,Alternate}},
% {Size={19.91-},Font=*Display, Ligatures=Rare, Contextuals={Swash,Alternate}}},
%UprightFont=ArnoPro-Regular,
%BoldFont=ArnoPro-Bold,
%ItalicFont=ArnoPro-Italic,
%BoldItalicFont=ArnoPro-BoldItalic
%]{Arno Pro} %
\begin{document}
I am \textbf{attempting} \textit{some} math:
\[\oint\vec{\text{E}}\cdot d\boldsymbol{\ell}=0\]
Again, some more: $\vec{\nabla}\times\vec{E}=0$
\paragraph{Example:} One more:
\begin{eqnarray*}
\bigintss\left(\frac{x^2}{x^{\frac{1}{2}}}-\frac{2x}{x^{\frac{1}{2}}}+\frac{1}{x^{\frac{1}{2}}}\right) dx&=&0
\end{eqnarray*}'
\end{document}
The following picture is the result of MinionPro (running luatex in the terminal):

While this is the result of ArnoPro (running xelatex in the terminal):

Note how the ArnoPro text for some reason looks a bit.. choppy, compared to MinionPro, for some reason when I run (for ArnoPro) xelatex doc.tex in the terminal it turns out like this (i.e. the top parts of e and o letters, among others, are missing). But when I look at other documents created with ArnoPro, this isn't the case and it looks fine! That's another issue I'm concerned with.
Apart from that issue, you can see why I would want MinionPro for math as ArnoPro math doesn't have much support. I could use MnSymbol for ArnoPro but the integrals and some other symbols just look terrible, and I think the letters in MinionPro are better suited for math purposes at least, so I'd prefer simply having MinionPro for math and ArnoPro for text. How can I do so?
Also, does MinionPro have enough symbols for higher-level math and physics (i.e. graduate level of study) as other packages like amsmath do; if not, what are your suggestions for other packages so it blends in well with ArnoPro text like MinionPro math symbols do? I'm entering 4th year of my undergrad and I'd just rather have these worries dealt with now rather than later.
I have quite a few other questions but I feel it would be way too long to add here, so I should probably save those for another time.

onlymathoption? — in which case thetextlfoption is useless, and perhaps harmful. A remark aside: you shouldn't useeqnarrayas it produces some bd horizontal spacings. Use one of thealignfamily instead. – Bernard May 07 '14 at 20:20onlymathand the coding doesn't work well at all with ArnoPro; depending on what I do with the remaining code (after MinionPro), it either sets the text font to default Computer Modern or it doesn't function altogether (probably because I don't know how to code it). So unfortunately that option did not do much for me :( – Alborz May 07 '14 at 20:36\usepackage[MnSymbol]{mathspec}I get something pretty similar to the math fromMinionPropackage. By the way, the “choppy” is just from your previewer, it doesn't happen in my case. If you just want text in Arno Pro, and math in Minion Pro:\usepackage[onlymath]{MinionPro}\usepackage{fontspec}\setmainfont{Arno Pro}works. – Manuel May 07 '14 at 20:57\usepackage[MnSymbol]{mathspec}with ArnoPro results in entirely different integrals (and the\ellsymbol reverts to Computer Modern font) and ArnoPro lettering in math which I would like to avoid; I'm curious as to how you have obtained something similar to the pictures I have shown above? Also, using your final line of code results in the similarly undesirable integrals (but the\elldoes work properly here) and the paragraphs/in-line text are not bolded or italicised at all. – Alborz May 07 '14 at 21:15\usepackage[minionint,mathlf,onlymath]{MinionPro}. http://i.stack.imgur.com/EL3az.png – Manuel May 07 '14 at 21:25mathspecwith Sabon Next LT Pro. Unfortunately, the side bearings weren't very good and I had to go back to MinionPro with optiononlymath. Btw I have a lot of errors with Arno Pro, that seem to be connected with theSizeFeatures=command. As long as the Size Features contents is commented out, it compiles fine; as soon as I add one, I obtain a lot of errors ~ 40). – Bernard May 07 '14 at 22:30