Problem with biblatex for "harvard style" author-year citations

Question

So for my bachelors thesis, I want to use the "harvard" citation style where it puts "authorX and authorY (Year)" if the cited paper has 2 authors and "authorX et. al. (Year)" for papers with 3 or more authors. This is working fine for the most part but I have a couple of sources where this doesn't work. Problem number one is that on some citations it prints "authorX, authorY, authorZ, et. al. (Year)" instead. Problem number two is that for a few cases it also prints the Authors first name or their initials, I only want to have to last name on all citations. I imported biblatex like this \usepackage[backend=biber, citestyle=authoryear-comp, bibstyle=numeric, maxcitenames=2]{biblatex}.

Some examples for the wrongly cited papers in bibtex:

@misc{Papernot.11142015,
 author = {Papernot, Nicolas and McDaniel, Patrick and Wu, Xi and Jha, Somesh and Swami, 
 Ananthram},
 date = {11/14/2015},
 year = {2015},
 title = {Distillation as a Defense to Adversarial Perturbations against Deep  Neural 
 Networks},
 url = {http://arxiv.org/pdf/1511.04508v2}
}
@misc{Goodfellow.12202014,
 author = {Goodfellow, Ian and Shlens, Jonathon and Szegedy, Christian},
 date = {12/20/2014},
 year = {2014},
 title = {Explaining and Harnessing Adversarial Examples},
 url = {http://arxiv.org/pdf/1412.6572v3}
}
@article{Lecun.1998,
 author = {LeCun, Y. and Bottou, L. and Bengio, Y. and Haffner, P.},
 year = {1998},
 title = {Gradient-based learning applied to document recognition},
 pages = {2278--2324},
 volume = {86},
 number = {11},
 issn = {00189219},
 journal = {Proceedings of the IEEE},
 doi = {10.1109/5.726791}
}