Vernon Vassallo

Hi,
I love reading everyone's post late at night and all the great advice 'round here!

I have a 2014 e550 coupe with the amg package. I've had it about 8 months, put about 10k miles and am ready to take it to the next level, I think I'll tune it at the end of summer. I'll likely go with DME as it seems to have the best price per horsepower/torque I could find. They claim 600 hp and 750 ft/lb on stock internals for ~$1800. (see here https://dmetuning.com/products/mercedes-e550-2014).
From reading others post it seems stage 2 without turbo upgrade is the most bang for your buck with the m278.

My car is mostly black with chrome grill, lip, rear emblems and tailpipes. Windows, trunk chrome and part of the grill have been vinyl wrapped black. Right now it has the stock amg wheels (18x8/8.5). I would like to upgrade to Vossen vsf2 or comparable concave spoke design in silver. I haven't been able to find too many pics of the coupe with 20" Vossen's, this is the best looking one though: http://www.permaisuri.com/portfolio/...th-Vossen-VFS2 I'm not sure how much its lowered.
See also 20's on sedan: http://www.permaisuri.com/portfolio/detail/963/home

Some of the coupe:
Personally, I think this needs to be lower: https://www.fitmentindustries.com/wh...s2-stock-stock
Damn near perfect IMO: https://www.facebook.com/photo?fbid=...t=o.6604386669

My questions:
1. 19 or 20? Considering the power gains of a tune, is it foolish to consider 20"'s?
2. I have the adaptive suspension i.e. a button on the center console that stiffens/loosens the suspension. If I use lowering springs will this system continue to work?
3. Thoughts on DME tune? Any recommended accompanying upgrades?
4. Anything I should know/do. I bought her with 65k miles, full-service history, and have taken very good care including regular maintenance.