I think most of the features in question have negligible differences between any cameras.
2: You are correct that the higher resolution of picture takes up more space but the storage capacity of a camera is dependent on the size of SD card used. A few can accept usb storage devices but most still use SD cards. Some of the older cams were limited to 2gb but i think anything now will take a least 8gb which is thousands of pictures.
3: Trail cams now have unbelievable battery life. A cam I put out this year in July has lost 12% battery over 6 months and taken 10,000 pics and maybe 500 videos. Having said that, white flash and video will run batteries down quicker, but I wouldn't worry about putting a solar panel up.
4: Water proofing isn't really a concern, but I have had insect problems. In my area, ants love batteries so how the battery compartment closes does end up being fairly important. As a side note, im no longer allowed to open cams in the house.
5: Most cams now-a-days allow you to imput a location into the data stamp and have date and time. Some also have temperature, barometric pressure, and/or moon phase. Really just a personal preference.
6: Im not real familiar with cams that send pictures as that crosses my personal line of too much technology (thats a topic for another thread) but my understanding is that they do need cell service and only send a low res pic but store a high res pic. I suppose in a private area with tresspasser trouble they could be useful but they are expensive and you also have to purchase a data plan from a phone provider.
8: As far as being quiet, I think all digital trail cams are about the same, but the old 35 mm cams could be heard from quite a ways off.
I think there are really only two features that separate trail cameras photo quality and flash type.
1: Photo quality is where you get what you pay for. I find there are three classes of trail cams; low quality <$90 this includes all wildgame innovations, all moultries, bushnell, new cuddeback, ect. Then there are the mid-range quality $100-$220 includes old cuddebacks, browning, covert, ect. and High quality >$250 and is made up mainly of reconyx. I can't afford the high-end but if you look at samples, you can see why they cost more. For what I do, the low quality cams just don't cut it. I do have a few but I have to use them as prospecting cams to see if an area is worth putting a good cam up. I just cant trust them to give me reliable data on what a specific deer is doing. As an example, this year I have two ten-pointers that look very similar. One is about 2 inches wider, the other has g1s that pitch slightly inward and has a right g4 about 2 inches longer. If I used a cam that didn't give good pictures, I wouldn't be able to tell them apart. Some people might not think that is a big deal but that is the difference between knowing one beds to the north and comes through every 6-8 days, and knowing that the other comes from the south every 1-2 days.
7: Flash type is probably the most debated feature. There are white flash, Infrared, and Black Flash and the only difference if wavelength of the light emitted. I haven't used any black flash so I can't speak on those. Personally I would rather have the best pics I can so I like white flash but there are much fewer available than there used to be. Some people will claim that white flash will scare animals but I think that has much more to do with the animal than the light. I have had deer get there picture once and then never go by that camera again, but others that don't mind the flash and will stand there getting their picture taken over and over. I think the same holds true for the ir cams because I can see the IR flash on cheap cams so I know the deer can.
Everything comes down to what you want out of the camera. If you need details about specific animals, stay away from the low-end. If you just want to see that there is game in the area, you can spend less and get a couple cams. Figure out what you want (including budget) and match a cam to that. Don't ask a cam to do something it can't do, you will be disappointed.
"You have reached the pinnacle of success as soon as you become uninterested in money, compliments, or publicity." - Eddie Rickenbacker, WWI fighter pilot
"Never mistake hope for a plan." Herman Edwards