A few questions about Everlast MIG welders...

I plan on buying a MIG welder in early spring.
Two things I want to have are:
1)The ability to weld Aluminum
2)120/240v option

I am looking at the I-MIG200 and see that it has a built in spool gun capability for Aluminum. I see that the SM200-N spool gun would be a perfect match. It also says "Miller compatible spool gun", does this mean it will work with Miller welders?
Will Miller spool guns work with the I-MIG 200?

Also in the description for the I-MIG200 it said....
"Equipped with a unique Stick weld function, the Power I MIG can also double for a scratch start TIG power supply"
I have no clue what this means? I can use the I-MIG as a TIG welder?

Another thing I'm wondering is what is the maximum thickness material you can weld with the I-MIG200 plugged into 120v?

I'm just trying to narrow down what I need/want so any help is appreciated.

Spool gun is out of the same factory as many of Millers, that is what it means. Connections are different, though gun is essentially the same.

Any DC CC machine can be made run a tig rig in a pinch. You have to supply torch and connections.