Parentheses around year, "normal number" in footnote and a word before footnote

Question

I've got three problems with my document's \footcite for which I can't find a solution. My MWE is the following:

\documentclass[%
draft=false,%
paper=a4,% 
fontsize=12pt,%
]{scrbook}

\usepackage[%
 backend=biber,%
 style=authoryear,%
 bibstyle=authoryear,%
 citestyle=authoryear,%
 sorting=anyt,%
]{biblatex}

\addbibresource{\jobname.bib} 

\begin{filecontents*}{\jobname.bib}
@article{Hong.2018,
 author = {Hong, KiHoon and Park, Kyounghoon and Yu, Jongmin},
 year = {2018},
 title = {Crowding Out in a Dual Currency Regime? Digital Versus Fiat 
Currency},
}
\end{filecontents*}

\begin{document}
Sentence~\footcite[S.~4]{Hong.2018}
\end{document}

Now I want the following three things to change in the footnote:

1. Put parentheses around the year (just the year) not the pagenumber
2. Write "Vgl." before the footnote begins (after the number of the footnote)
3. Write the number of the footnote as "normal number" not as an exponent.

The current output:

¹Hong, Park, and Yu 2018, S. 4.

should look like this:

1 Vgl. Hong, Park, and Yu (2018), S. 4.

What is the easiest / best way to make this happen?

Answer 1

Point 1 is fairly simple if you use biblatex-ext's drop-in replacement for authoryear, ext-authoryear. Then you only need

\DeclareInnerCiteDelims{footcite}{\bibopenparen}{\bibcloseparen}

Point 2 can be achieved with the optional pre-note argument

Lorem\autocite[Vgl.][380]{sigfridsson}

Point 3 can be achieved with

\deffootnote{1.5em}{1em}{\thefootnotemark\enskip}

In total and keeping in mind my comments under the question (1) that sorting=anyt is not really appropriate for authoryear-like styles since it bases its sorting on the alphabetic label of the style=alphabetic that is not present in authoryear-like styles, (2) that style=authoryear, bibstyle=authoryear, citestyle=authoryear, is the same as style=authoryear and (3) that there is no need to specify "S.~" manually since biblatex adds it automatically if appropriate, we get

\documentclass[fontsize=12pt,ngerman]{scrbook}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[
 backend=biber,
 style=ext-authoryear,
 autocite=footnote,
]{biblatex}

\DeclareInnerCiteDelims{footcite}{\bibopenparen}{\bibcloseparen}

\deffootnote{1.5em}{1em}{\thefootnotemark\enskip}

\addbibresource{biblatex-examples.bib} 

\begin{document}
Lorem\autocite[Vgl.][380]{sigfridsson}
\end{document}