When I was doing extract boils, I'd start with 6.25 gallons in my 10 gallon kettle for a 60 minute boil, or 6 gallons for a 45 minute boil, and end up with a bit less than 5.5 gallons in the carboy. I typically lost a bit over a quart racking off the trub at the end of primary fermentation, and a bit less than a quart racking off the remaining trub and dry hop pellet mush to a keg.
Most of my brews then (and now) hover in the 60 point range, but with the extract I'd get half the gravity from DME added at the beginning of the boil, and the rest with LME added in the last 10 minutes. I often used hopped LME and didn't want to lose the hop character from excessive boiling.
Bittering, flavor and aroma hop additions were no different with extract, partial/mini-mashes, or full grain. Same strains, same schedules, and pretty much indistinguishable results.
hth
Cheers!