Sorry I’m using the 1/8" two flute endmill that came with my Nomad 883 pro. They’re uncoated.
NOW WE’RE GETTING SOMEWHERE! 
I’m cutting 6061 (not sure if it’s -T6).
The most common variants all machine similarly. Let’s ignore this for now. In general, one needs to know the specifics of the metal they are machining. My 6061 is 6061-T6511 (the 511 is getting super specific; not pertinent to this issue). Better to know than to not know… knowing allows for optimizations.
I’m very willing to buy different cutters if it’ll get better results. especially faster roughing.
ZrN or TiB2 will allow modest improvements in speeds and will increase the life of the end mill. Well worth the extra expense. C3D stuff is pretty good… but one can do a fair amount better. More below.
I’m also willing to change alloy.
No need. 6061 is awesome. In the future, for general work, T6 is an excellent choice. T6 is very common so I wouldn’t be surprised that you have it. I would stay away from T1 until you’ve got some experience - and need it.
After my test cuts and plugging in the values to a SFM and chipload calculator my next test was going to be 10krpm 20IPM so it sounds like that’s a good combination.
Yes, that sounds good.
Do you recommend any specific end mills?
Read my posting… I mentioned it above… it’s all there! 
Before you order PM me and we cover the details.
What depth of cut do you use?
0.04. I would try 0.02 for your current tools. If you like that, try 0.03. Coatings get one extra distance.
Do you have any recommend settings for a finishing pass? Specifically for getting the best top surface quality?
6-10 IPM depending on the desired finish quality.
mark