they'll fit on your pista, regardless. it's just a matter of buying them. they're supposed to be really strong but real heavy. i'm getting them because yes for looks and they're also real strong and i'm very careless.

i've never heard of bicycle outlet. those are good prices. they're usually like 250 via bikesmith on ebay.
so yea, no lockring means you can't just put them on. you'll need to take the cog and lockring off your alex's and put them on the velocity's. let the LBS do it for you. they're machined for brakes if you want that, too.

oh and get toe clips. yes they're essential for stopping if riding brakeless, but also if you're pedaling really fast and your foot slips, bad things happen. most common are mks steel toe clips that cost like 15 bucks ish. get new pedals while you're at it, like some mks sylvans (track, stream, touring, gr-9, etc). that's just the most common. that's if you want to wear regular sneakers while riding.

clipless pedals are another story, and another couple hundred bucks.