let's break it down by issue.
The passenger side window problem is very likely a bad motor or regulator assembly. Pretty common on these vans. This is a job I wouldn't suggest for a novice mechanic, as it can be quite involved.
If you have a roof rack, it's possible you're getting water through the mounting holes, it's running along the headliner, and coming out the passenger side. It's also possible that debris has once again gotten into the windshield cowl and plugged the drain. (I assume the passenger leak is just water, not coolant). The roof rack can be sealed by a novice mechanic by removing it and putting silicone sealant on all the bolt threads, then reattaching it.
The starting problem sounds like a bad connection. Either a loose or corroded/greasy battery cable would be my guess. IF your van has the theftlock radio, and the theftlock light on the front is lit, make sure you have the code before you unhook the battery, or your radio will be rendered useless.
Front brakes are fairly simple, so buy a repair manual for your van (about $15) and follow the proceedure. Make sure you replace/resurface the rotors or they will squeal. Also make sure you tighten the lug nuts to spec (100 ft/lbs) or your rotors could warp.
Depending on the mileage, you're probably in need of a trans filter service. Make sure you just change the filter, and the fluid that comes out when you drop the pan. DO NOT let them talk you into a fluid exchange, or you'll be replacing your transmission soon (unless the van has less than 50,000 miles). I wouldn't switch to synthetic, as there is no real advantage in a daily driver car. Trans-x and Seafoam are both excellent additives for freeing up sticky shift valves, as is Lucas trans treatment. Add a can of one of those when you do the filter change.