yep autoglym shampoo is fine, and yes just give them a thin layer of 915 every time you wash them to top up the gloss and protection, if you have the option of taking them off for winter then do it as this will save them tbh, if you are keeping them on then you must keep a good routine of keeping them clean and protected or you will be wanting to get them refurbed in 12 months time. polished rims are well nice but need alot of care and attention unfortunatly.
bilberry wheel cleaner is a good cleaner for regular cleaning but not so good if you let your rims get quite manky between washes, it dilutes down nicely too.
dodojuice mellow yellow is a safe wheel cleaner and worth a punt, basically look on whatever website your going to buy it from and have a good read through the various wheel cleaners, they are all roughly the same in chemical make-up and all serve the same purpose just make sure its ph neutral and your sorted.
Dan