ok...

i'd recommend something with 2,4-D and/or dicamba in it to control dandelions and clover. read here for exact timing and application tips: http://ohioline.osu.edu/agf-fact/0402.html
i don't know what's in the ortho hose system, so until you find out, i'd stay away from that and I would suggest a granular application, the coverage will most likely be better that way believe it or not.

don't worry about fertilizing grass too early, this has always been a point of contention for me. definitely don't wait 4-6 weeks. when I seed grass, it usually gets fertilized within a week or two of it emerging from the ground. i would recommend a balanced fertilizer since your root systems may be a bit compromised from grub damage you didn't see, something like a 10-10-10 or similar. if the first number (nitrogen) is higher, that's fine. or if they're similar, go for it, don't worry too much about the numbers, just try to get around a half pound of nitrogen per 1000 ft. sq. if you need someone to calculate the exact amount of fertilizer for you, let me know, but we will need the approximate square footage of your yard and what fertilizer you end up buying. oh yeah, and do granular fert also.

it shouldn't really matter, but i would do the herbicide treatment, wait a few days or a week and then do the fertilizer. fertilizer obviously isn't selective and will feed the weeds as well, so i would try to weaken them first and then give the grass a nice shot of food.

i wouldn't bother with the grub treatment, it's such a variable thing. where they are one year has almost no forbearance on where they appear the next. and you can fertilize/water your way out of minor grub damage, which it sounds like all you had. plus, i don't know that sevin or dylox are available for homeowners and anything they try to sell you in the store (lowes, home depot) ain't gonna cut it. preventive applications for white grubs are generally done a little earlier than late may anyway... again, just leave the grubs be, i'll bet you won't even have any damage this year (famous last words... ;)

good luck.

Unless I know what your lawn needs, I can't really recommend what the numbers on the fertilizer should be. If your soil already has a lot of P in it, using a fertilizer that contains P can cause problems in the water supply. In my area, the best fertilizers are usually fertilizers with 0 for the second and third numbers.

A liquid herbicide is usually easier to get to get evenly on the weeds. I would definitely check the label before using it in the areas where you've recently seeded new grass. Spring is not the best time to seed, so you may lose a lot of that grass in the summer.

Weed and feed products are not the most effective way to combat weeds. Most of the weed killers work best when the weeds are actively growing, so some people increase the effectiveness of the herbicides by fertilizing first, then using the weed killer about a week later.