1. Just buying the upgradable fare doesn't initiate the request for an upgrade. I suddenly can't remember if I was finally able to make the request online last trip, but in the past I've made the reservation and then immediately called to get the upgrade. If it's available, it will be processed immediately. As often as not, it'll take a few days to clear. The miles will be subtracted from your account, but if the upgrade ends up not clearing the miles will be redeposited immediately at that time.

2. There are numerous ways to check upgrade availability before making the reservation; check the stickies in this forum to learn about them. Unfortunately, with my system here at work I can't go check while I'm in the middle of typing this message. For the amount of the fare, just paying the extra few $$ to make the reservation online might be worth it to you, as well.

3. Yes. Upgrade awards are one-way deals, so no problem upgrading in just one direction (I did that once before I'd built up enough miles to upgrade both ways).

This, incidentally, is just about the only way I ever spend my miles. I haven't flown steerage across an ocean for several years now. I'll gladly use the miles to upgrade ORD-LHR (my usual route) and ORD-HNL (an even longer flight on an inferior airplane).