You would need some support in the framed wall, but this'd probably be just slapping enough studs onto the existing ones under the beam, so the "post" is the same width as the beam. It doesn't take nearly as beefy a post as the beam is in most cases. I don't have the beam calculator program at home that I use at work, or I'd run the numbers for you. I don't do design checks much anymore, so I might make errors. Any lumber yard that would do the beam calc for you could check the post for you too. Most do this free of charge if you're likely to buy the material from them, and most building depts. accept these calcs without an engineer's stamp on them if the guy doing the calcs entered it right.
I'd look first a beefing up the beam that's already there. This'd probably mean having to cut the joists back to allow you to sandwich more 2x onto the existing beam, but you could do it one side at a time, or all of it on one side. You'd only have to put up temorary floor support on one side that way, and could leave the existing posts in place until your done. Increasing the span that much though, your probably going to have to do a glulam, lvl, or such to keep the size down. This'll be a hell of alot more work. I'd probably put up temporary support under the joists on either side. take out the posts and existing beam. Then come up with a way to lift the new beam in place at the back wall, then you might have to remove some studs on the front wall to allow that end to swing over into place, and then arrange to lift that end up. It helps to have some strong guys around with common sense, especially ones that have experience with construction or moving large objects. I was the company carpenter for a plumbing contractor in central Oregon for a few years. I learned alot from these guys about moving really heavy objects without resorting to manhandling them. If the building economy has gone in the tank in your area as bad as most the rest of the country, you may find a contractor that will put the beam in for you at a reasonable cost, and you could do the rest on your own.
The permit cost is usually based on a percentage of the value of the work done. Even though you may place the value of your labor at zero, they'll count it in toward permit cost. Since your only buying one beam, and they'll probably only make one inspection, you may get away with the minimum fee.
Since this is a garage with living space above, you'll probably have to cover the framing up with drywall on the garage side to act as a fire separation between.
Installing a new window where there wasn't one isn't always simple. You've got the gravity loads like what we've been discussing, i.e. what's the wall holding up where you want the window. You've also got what's called lateral load too. When the wind hits the wall and roof of the house, the house resists this load through the walls at right angles to the wall being blown against, and by the roof and floor diaphrams in the house. In most houses this means you have to have a percentage of those walls that don't have holes such as door or window openings in the wall sheathing. These full height walls are referred to as brace panels or shearwalls. Code generally also requires brace panels at the corners of the house, or within a permittable distance from the corner. Engineers have ways do design to get bigger or more openings, but charge money for this service. I'd talk to the building dept about what you want to do, and they'll tell you if it's do-able. You may also run into plumbing, or other utilities in the wall right where you want the window, this can be a real pain. Alot of that can be deduced before hand, if there's a bathroom on the floor above where you want the window, there probably plumbing in the wall below. Walking around the house and looking for plumbing vent pipes can help too. It's real bummer to find this stuff after you've knocked a hole in the wall, and the inspector's telling you now you need a plumbing permit to move the pipes.
If you want to do the beam and the windows, do them all on one permit, it's cheaper. Just remember to ask the dept as many questions you can think of beforehand, there time at the counter with you is free to you, someone elses permit fees paid for that until you buy yours. You seem like an intelligent guy, so they'll probably be glad to discuss it with you beforehand, photos help too. Call first, and ask what the best time to talk to them would be, and try to meet them at that time. If you send your wife in to discuss this with them, make sure she has a very good understanding of what's going on, if your doing the work, it's best if you go. Bring her with you though, so she's kept informed, she's likely to be the one meeting the inspector at your house, and it works better for everyone if she's in on it too.
Moving or adding electrical outlets is usually easy, and electrical permits for this run in the 50-100 dollar range. In our dep't it starts at $54, but if you add more curcuits on it's $4 a ckt. So try to figure out all the electrical stuff you want to do, and get it on one permit.
