getting new sod at the new house in like 3 weeks. what do I need to do to it?
Water it. Super easy!
is there a nationwide company for the fertilizing/aerating/etc. that I should use or is a local place better?
Don't hire a mow and blow guy to do your fertilizer and chemical work. As a general rule, they are not as compitent as a lawn care company. Local, regional, or national doesn't really matter. A company mentioned earlier might be big, but they suck in some areas and consistency is not their strong suit.
What I would do is keep my eyes open and see who the people with the best yards are using. Might be national, might be local. Tell them you want your grub treatment done in early July, regardless of what they say their schedule is. DO NOT LET THEM PUT IT OUT IN MAY! Also, I can tell you what product to use for best results, but that might be a conflict of interest. Just ask for the most tested and proven grub insecticide on the market.