Congrats on starting out on the bike.
Perhaps I can answer training diet in two ways
I too restarted on the bike in mid 40's with aim to get fitter and lose weight. I currenty ride around 120 to 180 klms a week with the odd ride about once a fortnight of 60klms + adding to regular rides. I generally plan allow 1-2 rest days a week.
My general diet, including red wine, (purely medicinal
) has not changed dramatically, except I tend to eat less at meal times. I can't explain why but I do feel 'full' easier exercising regularly. Diet is pretty good generally, not much crap, just too much for lifestyle. Generally I hate fast food and would rather have an egg on toast as my fast food meal in favour of Maccas and alike. Ideally I aim for another 10kgs loss, but another 5 would be fine. Basically like many my age it was more lack of exercise and too much food. I chose exercise as it is more fun that starving onself. In 2 months I have lost 8+kgs and this continues as I now take on greater challenges during rides such as hills.
For individual rides over 1.5 hours I take a sports drink (750ml bottle) + water (750ml drink bottle) + fruit (usually banana - top cut to help access whilst riding) and either fruit jube type lollies, such as snakes or perhaps a fruit gel. More often than not I return with lollies and fruit intact but most of the drink bottles gone on rides up to 2 hours. I found this article quite useful as a guideline
http://www.cyclingtipsblog.com/2008/09/the-long-ride/. I plan to do the 140klm Rainforest Ride at Apollo Bay in November and plan a bottle of sports drink per hour plus carry lollies to top up but will probably prefer to stop to buy lunch on the way if they have sandwiches (& coffee
). You can find some sports drinks will sell sachets of powder sufficient to fill a water bottle so you can mix up at drink stations. Alternatively I sometimes carry individual powder servings in self seal sandwich bags. I find the gels seem to make me 'thirstier' and sometimes give 'tummy' ache. I am not riding in races so a couple of minutes mixing drink myself is no big deal and I mix to y preference. This way I can be self sufficient so my family can go about their own activities. If racing, of course, a ground support crew to mix and feed is a more essential 'luxury'. Interestingly on the cyclingtips blog, he suggest a simple 500ml flavoured milk as a recovery drink 'cos it provides sufficient protein etc to aid muscle recovery following a big ride.
For shorter rides up to 1.5hours I find a normal meal within 1 to 1.5 hours before the ride is sufficient and only take water and/or a half strength sports drink solution probably more for flavour or encouragement to ensure I drink it especially on the hotter and windy days. Even on 1.5 hour rides though I will start out with 2 water bottles. A top up drink before leaving helps too. I usually don't drink everything but at least a water bottle full.
The only time I really 'tanked' was after an early work start without breakfast (2.5 hours then went on ride) and riding 35klms into very heavy wind. I put it down to riding without food intake for close to 12 hours as major contribution. Lack of sufficient hydration accompanied this too. The legs were pretty sore and 'crampy' for 2-3 days following this but energy drain ok after breakfast and lots of water.
A couple of months in muscle soreness between rides is rare and light. In fact in some ways the minor pain is a pleasant reward for a job well done - climbing a big hill or increasing avg speed by 1kmh+. Again for me using the sports drinks & water indictes that much of the muscle soreness was due to losing salts and insufficient hydration during exercise. By minor pain I mean noticing 'burn' when tensing leg muscles at rest. Day to day activities such as climbing stairs or walking are not hampered. Once or twice I've had cramp issues at rest and magnesium was suggested, but I have tended more to bring forward the rest day to allow recovery or at least a recovery ride of lesser distance and effort.
I hope this answers questions about training food both general diet and specific rides.
. Basically for the past 8 weeks been riding 4 times a week. 
