I would say don't stick to one brand, and also join detailing world and prepare to spend hours (and lots of money) discovering what you need
Out of that lot you listed, I'd only purchase the following megs products:
Megs gold class shampoo and conditioner (can't see why AG is recommended over this, it's not bad really, better than their NXT stuff)
Megs nxt metal polish (although autosol is a classic!)
Megs hot shine tyre spray
Megs quick interior detailer (ideal for quick wipe overs)
Megs applicator pad (generally good for applying stuff!)
Then just bulk buy microfibre cloths from ebay or wherever, ideal for putting on and taking off products.
The megs 3 stage stuff isn't that good as a whole, i.e. their wax is awful and the stage 1 is a chemical cleaner as opposed to a abrasive cleaner. Stage 2 is good if used as a glaze though.
What you need to remember when it comes to paintwork is thoroughly clean and clay the paint so you get a mirror smooth finish. Once you have your ideal look, you can enhance it (with a glaze) then you must protect it with a decent wax and/or sealant. After the initial application of wax, you will only need to lightly wash the car to bring it up to a good shine, and top the wax up every couple of weeks or so.
Waxes, you're talking £10 up to thousands of pounds, so it's whatever fits your budget really