You won't want to run an end mill larger than 1/2". Anything bigger is highly likely to chatter and bog the motor down.
As for end mills? Get cheap two flute ones since they're going to be broken by the students most likely
Honestly, I think you've done your homework and walking in well educated.
I'm not sure about the boring head. I got a 3" indexable tooling set from Shars that is OK. It cuts well and leaves a nice surface finish; however, the adjustment screw has quite a bit of backlash that I want to try to resolve. I think LMS and Shars are made by the same manufacturer.
If you want to go CNC, you can most likely skip the DRO.
Get a good machining vise. The Shars ones have been said to be pretty good for the dollar, and for FRC applications "good" is usually good enough. For the G0704, a 4" vise is probably the right size unless you want to machine the end off of a 5" to clear the column on some cuts.
I really like my Glacern ER16 and ER25 tool holders, vises, and face mill. I bought them in November when everything is a lot cheaper (Black November sale).
Always try the sponsorship card when acquiring new hardware. We tried Grizzly, but I don't think they do donations or educational discounts of equipment. It doesn't hurt to ask.
Monster Jaws sells cheap ($80-85 for 10 pairs of 4") soft jaws that you might find useful later on.
And whatever you do, take that mill completely apart when you get it and clean and relube
everything. You'll find out why as soon as you use it the first time after reassembly. You can tram it following the hossmachine guide on YouTube. It's pretty easy to do and you should be able to get it aligned very well.