I'm a firm believer in sod instead of seed but make a couple calls and get prices. Remember that if you seed you really need to do it 3 times, fall, spring,fall in order to get a thick, full lawn. Also seed needs to be kept 'moist' until it really 'takes', something you need to do EVERY day....
Sod is a one day labour event, then a heavy watering, every 3-4 days for 2 week =-.
Locally a roll of sod is 2x5 feet, so your lawn would need 3500/10 = 350 rolls. Say $5 per roll, less than $2000. Grass seed cost, you'll have to figure out...depends on mix/blend of grasses and bag size. Obviously you need a spreader and a roller. Spray whole area with 24-d to kill weeds .
new neighbour is 'hydroseeding', after I harrow his yards to prep for the seeding. Maybe an option for you ??
Sprinklers are always added AFTER lawn has become 'established'. You'll need several 'zones' and a controller. If you do install, take pictures and make a map ! Friend has a leak 'somewhere' in one zone. While usually it's a connection at a head, he suspects the cable guy nicked the feed pipe.PITA ,need to make a conductivity probe then wait for real dry ground to locate it.