fart
Quite right in your assumptions. If you need to make an LVO approach you need to check with ATC that they have LVO's in force to ensure protection etc. So it follows that you would not want to be making an autoland in LVO conditions if ATC were still using the CAT I holding points.
You are also correct in thinking that the spacing is increased significantly in LVO conditions (any ATCO's got the exact gen?) and delays are to be expected so make sure you have plenty of fuel for going round in circles at your destination should the forecast be bad. It's also worth considering your strategy when you get to the overhead and enter the hold. ATC will generally give you the expected delay in the hold, if that is going to put you close to a diversion decision then it may be worth diverting early, getting into your alternate and re-fuelling with plenty (golden rule; don't tech stop and end up diverting again because you didn't put enough on!) of fuel then race back to your original destination which is now less busy because everyone else has now diverted to where you've just been! Happened to us once going into Manchester early morning with no low vis forecast but LVP's in operation when we picked up the ATIS. Every man and his dog entering the stack (all with the same forecast as us so no-one had much fuel to be playing with) and we diverted before even reaching Dayne, refuelled at Brum as everyone else followed us in, departed and landed at Manch probably 30-45 mins before the next one!
125m is our absolute minimum as you point out the same rules apply for RVR reports. The reason for a departure alternate within a certain distance (I've flown with a couple of outfits now and one used 400nm and the other 250nm) is not down to ILS category primarily, more to do with worst case, i.e. engine failure on T/O which precludes an autoland (on the 757 you can only autoland with one engine if you have armed 'approach' prior to losing the engine), but that does lead to some debate on is it wiser to fly possibly a considerable distance to an alternate on one engine when you have a perfectly serviceable airfield in LVP's nearby (don't shoot me down I didn't say I'd do it, just there is a debate about it!). So even if the ILS was CAT III we couldn't make an approach in the EFATO case.
Hope that helps......there's tonnes more for a winters day reading!
PP