Hi,
Trying to address all your questions:
1. If it's only a month since your last HbA1C it may not be worth asking for another one just yet. You already know it's come down a lot since diagnosis; your daily control (i.e. your blood glucose readings from your meter) will tell you more right now. But I think it would be worth trying to get another HbA1C in another month or two (i.e. so that it's 2 or 3 months since the previous one).
2. I don't use Lantus so can't comment directly, but bear in mind that side effects vary from person to person - Lantus isn't "bad" or "dangerous" per se, many people get on very well with it and others don't. I'll let those with more experience answer this further.
3. Alcohol can certainly lower your blood glucose over night. This happens because the liver usually produces glucose overnight, but if it has to do other work (in this case processing alcohol), that takes priority and it doesn't produce as much glucose. This has the effect of lowering your blood glucose. Beer has a fair whack of carbohydrate in it, so although it still has the same effect of reducing the amount of glucose the liver produces, you're also taking in carbs which will raise blood glucose - so this is why wine depresses BG more than beer.
4. Going low after breakfast after drinking - this is related to the above; your liver hasn't produced the normal amount of glucose so you go low. This is just something you need to be aware of and allow for (either by eating slightly more or injecting slightly less novorapid) - you need to learn your own body's responses to food, exercise, insulin, illness, and all sorts of other things so you can adjust waht you do to maintain good control.
5. As for the weight gain - it's completely normal to put weight back on after diagnosis. You've been without insulin (the primary "storage" hormone) so your body was unable to use the fuel you were eating, and was therefore burning your body's stores; it's now got access to insulin again so it's trying to replenish those stores. Don't worry too much about it right now. But essentially, the same rules apply as for everyone else - if you don't want to put on weight, don't eat more than you burn off. You'll probably find that limiting your carbohydrate intake (which in turn will mean you need a bit less insulin) wll help with weight control, as well as help your blood sugars.
Hope that helps, please post back with any more questions.
Cheers,
Nick.