Alpine climbing is peculiar in that in order to increase safety you tend to take less safety equipment! The reasons for this boil down to the fact that the biggest form of safety in the alps is speed. This is not a short sprint but an all day (or days) marathon. The more you carry, the slower and more tired you will be. Thus in order to have some degree of safety and comfort it is advisable for as much of your equipment to perform two roles.
Don’t carry both tape slings for the route and cord for prussik slings for glacier travel. Use the latter for gear on the route.
Take one of the new, small, lightweight head-torches such as the Petzl Tikka rather than the larger and heavier Zoom. Yes the latter has a brighter and longer lasting light, but the former is perfectly adequate for approaching routes over snow or ice.
Using lightweight walking boots rather than full mountaineering plastics can save weight and effort. Crampons do fit to them but obviously front pointing is not really an option.
Before turning in for the night on a bivvy, fill your water bottle since in the morning the cold of the night will have frozen most available water sources. Then store the bottle upside down. Ice forms on the upper surface of liquid so by overturning the bottle the ice will in effect form at the bottom enabling you to gain access to the unfrozen water "beneath".
A useful addition to your water bottle is a length of plastic tubing, similar to that used in wine-making kits, this may be used for sucking water from small pools of water found on glaciers or occasionally on routes without having to stick your face into the ice. If the tube is long enough then it may be used as a syphon to fill your water bottle.
If the route you are attempting is going to be a full day and you think that you may have to take an emergency bivouac then rather than taking full bivvy gear, tape a lightweight emergency blanket to the inside of the shell of your helmet. This adds only a few grammes to the weight you are carrying.
You’ve gone light(ish) and are settling down to bivvy. But once in your pit, you are cold. The way to avoid this is to ensure that before getting into your pit you are warm, then at least the bag can have some warmth to conserve. If you get in cold, the bag isn’t going to warm you up. Also make sure that your pit isn’t too big - if it is then every time you move you will pump the warm air around and possibly out of the bag, which is then replaced by cold air.