To answer your questions, I started at the gym and with a PT once a week from the start. I went to the gym twice a week then increased it to a third as well. I started eating just fruit in between meals and really didn't need anything else, if starving I'd have a one piece of bread sandwich, often when I got home from work, but this was rare. It was also useful my husband and I decided to go for a 30 min walk most nights which helped to burn a few more calories!
In terms of diet, I now have an occasional low fat lasagne or sweet and sour chicken, I do try to avoid takeaways, but these solve my need for the full fat versions. I have had 2 pizzas since Nov 2016! One was when I was on holiday and the other was a treat meal after running a half marathon!
What did help (and I know this won't work for everyone) was if my husband had a cake or a pizza I would have 1 mouthful, that way I didn't feel deprived and as though I couldn't have anything nice, I'd have 2 crisps out of his packet as another example.
I keep my meals very similar because then I can adjust snacks if I start slipping a bit or if I see the scales going down.
I've kept at it because I've needed to do it. Then because it was working, I was able to keep going if that makes sense. I've loved seeing the progress I've made, dropping 4 dress sizes, seeing my strength increase and my stamina improve. I have to maintain as there is no way I want to go back to where I was 15 months ago.