The pain will pass. The first few weeks are torture, then you can gradually increase the distance and eventually speed. My first ride back on the bike was whole 5 miles and it HURT! That was 4 months and 20kg ago. Now I back to 86kg for the first time in 15 years and I rode 120km last Saturday with no pain at all at a cruising speed of around 30-35km/h. Stick with it and you will see results.

As for supplies I carry a spare inner tube, patch kit, tire irons, water bottle, multitool, frame pump, and a presto to shroder adapter - very useful if you want to use the gas station compressors. If I ride for more than two hours I'll add water and food in a backpack.