camhabib- Welcome to Autopia!
To be perfectly honest, your inquiry is a bit too broad...sorta like "I'm living in an apartment and would like to build a house...how should I go about it?" I'll try to hit some highpoints and I'll base my suggestions on my perception of what you're after. A lot of people here would make this a lot more complicated, but I want to offer something that you'll consider realistically doable.
First, I'll tease you a little about being the owner of a new C4S who says he doesn't want to spend much on detailing supplies :chuckle: NO offense intended and since I have bought Porsches and other such toys showroom-new I figure I'm allowed to joke about it

OK, OK...getting to the real response here...
To wax/seal your wheels you'll have to really clean 'em up first. Then you apply multiple applications of sealant/wax (AKA Last Step Product, or "LSP"). Then you clean them with just car shampoo (wheel cleaner will also clean off the LSP), which means you need to do it before they get too nasty. I bet you'd end up doing more work for minimally better *potential* results.
While I do seal most of my wheels, on some I just stick with the wheel cleaner and IMO that's what's gonna work best for you overall. I'd just do them a little more often and follow up with a spritz of some good leaves-stuff-behind Quick Detailer ("QD") like FinishKare FK425 or FK146, which will provide a little help with regard to the brakedust being so tenacious. FWIW, that's what I did on most of my Porsches, the C4 included.
Additional thought- I bet your wheels do need a good, thorough cleaning, even if you're not gonna LSP them. See suggestions for all-in-one products a few paragraphs down under "Wax/etc.".
Washing- Nothing wrong with the Perls, though I prefer Griot's Car Wash over anything else. You could save money, and probably be just as satisfied, by switching to DuraGloss shampoo or even Meguiar's Gold Class. How To Wash is a very long article I haven't written yet (though there's an old version of my opinion around here somewhere entitled "Accumulator's Non-marring Wash Technique"). But it sounds like you're satisfied with your current wash regimen and that's what counts.
I would caution about the sheeting/evaporation drying though...even though I too have softened/filtered water, I can only get away with that when I use my CRS deionizer; even soft water leaves behind a light residue that I consider unacceptable. I'd do a light towel-dry after spritzing on a little FK425 or FK146 or even your spray wax. For the drying towels, I'd use the Ultra Soft Waffle Weave Drying Towels from
Aloha & Welcome to Our Oasis for All Your Auto Detailing, Auto Detailing Supplies, Auto Detailing Equipment, Auto Detailing Products, & Auto Detailing Accessories for all your Automobile Detailing but there are other, similar, towels on the market.
Wax/etc: IMO you need something better than just the spray wax. I believe you need to first properly clean the paint and then apply a real LSP. The spray wax is more of a now-and-then touchup measure.
For the cleaning, I'd suggest an All-In-One product such as Klasse All In One, Zaino All In One, 1Z Metallic PolishWax, Griot's One Step Sealant, or Autoglym Super Resin Polish. All work fine by hand and are sorta like "super cleaner-waxes".
In your case I'd probably go with the Autoglym Super Resin Polish ("SRP").
Then I'd wax it with Collinite 845 Insulator wax, which is inexpensive, user-friendly, and durable. You'll love it.
THEN you can spruce it up with the spray wax after each wash. Heh heh, if you try the FK425/FK146 that I mentioned for the wheels, you might never go back to the 1Z Spray Wax
Interior: What you're doing now if fine except I'd replace the Lexol with something from Leather Masters, Sonus, or 1Z. These days I only use Lexol on stuff like leather dog leads; there are better products for the (factory coated) leather being used in cars.
Big thing is to get one of those all-in-one products and a good wax like the Collinite. Just do your sideview mirrors as a test and I'm confident you'll be convinced...I bet I could pretty much offer you a money-back guarantee with zero fear of having to honor it.