I Have Just Been Prescribed Eltroxin For Hypothyroidism. I Have

I have just been prescribed eltroxin for hypothyroidism. I have a pituitary tumour and had POF at age 33 and am now 49. I gained 27kg in that time and could not lose it whatever I tried (diet, exercise). I suffer many menopausal symptoms including debilitating hot flushes. I developed melasma on my face and neck and my complexion went 4 shades darker than the rest of my body. I was on oestrogen with progesterone HRT (synthetic) for about 7 years and stopped them due to cancer fears. I'm thinking of replacing these hormones with bio-identical topical hormones (creams). My questions are:
1. Can balancing of these hormones be achieved through bio-identical topical hormonal creams?
2. How can I reverse the melasma issue? I have tried skin lightening creams but nothing seems to help. I seem to be encouraging the melanin every time I try this. This is a very upsetting problem even though it may sound as if I'm just being vain considering my other issues
3. I need to lose this weight and fast because the hypothyroidism has caused serious memory issues, aching bones, etc. Will the weight shift? Some report that they gained weight on eltroxin, should I be worried?
Does the loss of the female hormones cause one to gain weight? I have post menopause levels and I am suffering many menopausal systems even if it is years since the POF