I have been using cakwalk for a while now and find it very friendly and comfortable to use. I have become proficient in using it and would recommend it to you or anyone for that matter. Having said this I would say that most of these sequencers basically function in almost the same way since they are designed to accomplish specific tasks. I think you should use that program that u are most comfortable with and proficient in.
A lot has been said about protools as being the industry standard at this point in time and I must say that also at some points in time cubase and cakewalk were considered industry standards, so I will still ask you to go with whichever sequencer you are most comfartable with and proficient in as the term "Industry standard" is a pretty dynamics one and depends a lot on the research and new developments undertaken by the varoius software manufacturers.
As for the soundcard issue, I use a terratec EWS88MT and it has been pretty reliable so Iwill advice that any high end soundcard from a reputable manufacturer will do, the issue is likely to be your budget.
Anyway I hope that you make the right choice for you and will like to know what you resolved to do and how you progress from there.