I played it the day it was released on xbox, unpatched and all, and honestly I noticed very few glitches. Some glitches with the graphics here and there, nothing that isn't common in Fallout 3, the guns would occasionally rise above my head in first person or disapear all together though they were still usable and could be fixed by unequipping and reequipping the weapon, the load times would take upwards of 3 minutes between zones (but that only started to occur after 8+ hours of continuous play and would stop if i turned the xbox off for a few minutes) and two times it froze completely on the load screen forcing me to shut off the xbox and turn it back on. After the patch, the load screens don't seem to take as long after a lot of hours of play, though I think the longest I've played continously since release day is 6 hours instead of the 10 i did on release day, and the game has only frozen up once randomly after about half an hour of play.
all together, having put in around 90 hours so far, these glitches were uncommon and didn't affect much, but I suppose I could say the patch helped a little.
I've experienced these exact same problems. To larger/lesser degrees.
The weapon floating too high issue only happens when crouched so I believe somehow the code is leaving the weapon at walking height while putting your head at crouched height. Annoying when you suddenly lose half of your field of view but as you said, it only takes a couple of seconds to swap weapons.
The load time between areas hits me a lot sooner. Sometimes after only an hour or so of playing. LIke you, I've learned to just restart the box when it gets too long.
There have been lots of little WTF? moments when people are floating or stuck halfway through the scenery (rad scorpions mostly).
The busted Weathered 10mm pistol (ala white screen) svcked
The only really bad one for me is a story mission that is not complete but has no active objectives. Looks like I may have to switch factions mid-stream. (unless I find that it is waiting on something else to happen before it kicks back in)
I have noticed no difference at all after the patch (except maybe fewer underground rad scorps). Apparently the things they fixed weren't things I was using.
Still, I love the game and refuse to have a tantrum and stop playing. As with any game that lets me, I save often. I usually run two saves that I bounce back and forth on, saving over one and then the other. That way if my most current one is trashed I have one only a little ways back. I also stop overwriting saves every so often and create a new one. I have saves... saved... from about 30 key points in the game. I don't care what happens, I've got fallback in my Fallout.
I even have a save in the very first room of the game. : )