Like a couple of hours maybe? I don't think that you will be needed a lot of time to do this frankly. I just think that you need like less than 1 day, or maybe much less. So don't bother with this question and just start playing

I think that depend on what i want to buy. If i'm sure, than online is preferable and if i am not, than i'd rather go to some shop and search for needed item there, it is all simple