no you can't ride without the nuts on the cotters, they will fall out from vibrations, and you may have an accident and die. you may well have to take it to the LBS if you arent comfortable witht he removal. they don't respond well to force. i have never had to use more than 1 solid smack with a hammer, but it needs to be perfectly lined up.

after you get the cotters out and get to the bearings part of your project.

buy new bearings at the LBS, bring them a couple to get the right size. 24 bearings from the LBS cost me $1. and a new can of grease from the auto parts store cost me 3.99. and will last me many bikes. but your auto mechanic may give you a half cup of grease for nothing.

the grease is a solid, and will smear around the spindle like peanut butter. then you can attach the bearings they will stick around the edge nicely like a necklace. then put the spindle back into the bracket without touching the sides, like you are playing 'Operation' . at this point i stuck a small rag into the bracket to hold the spindle straight and level. Put more grease into the cup and then attach the other bearings. Once you line the cup up with the spindle, sneak the rag out a little at time so everything stays straight and level.

hint i didn't read: don't tighten the bracket as much as possible. i had to back mine out to a point where it spun freely.