I’ve never owned an electric, but I know a bit about them, so I’ll try to help.
The wider the path you can cut, the fewer passes you’ll have to make, which means you’ll be back inside quicker. I can’t say I’ve seen electric mowers above 18 or 19 inches, which is a drawback; compared to a 22 inch deck, a 19 inch mower will need about 6 more passes on a lawn 65 feet wide. Doesn’t sound like much, but when it’s 90+ degrees outside, every minute counts.
Voltage is going to affect two things: how long you can mow, and how heavy the mower is. More power means more mowing time per charge, but also makes for a heavier mower. Make sure you’re okay pushing a high-powered beast around before you take it home.
Mulching is definitely the way to go. I haven’t bagged clippings in 6 years. As long as you mow diligently, you won’t get big clumps of clippings on the lawn; clippings are mostly water, and they disappear quickly. Besides, why throw away all that fertilizer you fed to the grass? Leave the clippings there, and all that nitrogen you fed the lawn will go right back into it.
Sharpening a mower blade is pretty easy, and I rarely do it more frequently than once a year, at the start of the season. You can take your blade to a shop for sharpening, or you can do it yourself. There are lots of ways to do it at home; you could just use a file, but it’s easier to get a kit. There are sharpening kits that fit your Dremel tool (if you have one) for about $10, which includes a grinding stone and a guide that ensures the blade meets the stone at the proper angle. You can also get a kit that fits a standard power drill. If you do it at home, also look for a blade balancer, which is a little plastic doohickey you put the blade on to make sure it’s weighted the same on both sides after you take metal off. Unbalanced blades lead to vibration, which leads to mower breakage and/or accidents.
A hilly lawn is going to be a problem. For hills, I’d recommend a self-propelled mower. Self-propelled electrics are out now, but I haven’t used them or seen them in action. My gas-powered self-propelled mower rocks; at full throttle, I’d have to jog to keep up with it.
I can’t tell you much about wheel height, because I don’t get it myself. I’ve heard that the high-wheel models are easier to push and turn, but all my mowers have had standard wheels, so I can’t say that I know that’s true.
I’m not sure why you feel electric is the way to go; I can tell you that my mower goes through maybe a gallon and a half of gas a year, so it’s not particularly expensive or wasteful. New oil, air filter, and spark plugs each year adds maybe $9 to the maintenance budget. Having 6.75 horsepower really helps if you’ve let the lawn slide a bit or if the grass is wet. With an electric, there’s no “I’ll just mow it next week”; you have to be diligent, because your mower won’t be able to handle grass that’s too tall or thick weeds. If you do go electric, look into one that allows you to change batteries easily and keep a second one charged and ready, in case you can’t finish on one charge. That’s another advantage of gas mowers; I can just add more if I run out, while a battery takes hours to charge.