1. Agree the volume from the speakers should be equal. Mine are pretty close, but the top you can tell is softer than the bottom. Not sure if this can be fixed down the track or if the top speaker is just weaker.
2. I think it's to increase overall longevity of the battery. Google got burned with the Nexus 6P batteries degrading very quickly requiring a lot of repairs/replacements. The hotter batteries get while charging, the faster they degrade, so looks like Google is being conservative here.
3. My battery life seems to be the same. Though I think I read that the battery percentage indicator will no longer stay at 100% for an unusually long time now and will lower appropriately.
4. After the 8.1 sound update, I think video is superb. The stabilisation is insane and haven't seen a phone with better video stabilising.
5. Yeah the volume can get decently loud, but not extremely loud like the iPhone can. Agree I'd like to see this get improved.
I love Gmail and love the conversation style. Always have. You can change it on the desktop, but for mobile, maybe a different email client will change it for you.
My minor gripes with the phone:
1. I don't think the phone looks or feels as nice as it's competitors - the Galaxy S8+, Note 8, LG V30, iPhone X etc. I think Google really need to improve the look and feel of their device - it's a high end, expensive product, it should look like one. Hopefully getting all those HTC employees means the Pixel 3 will be something that looks spectacular.
2. I think a 6" screen is just too big for me. I'd like a 5.5" screen option, maybe the smaller phone move up to 5.5" and the larger one stay at 6".
Other than that really, I think the phone is superb. I like the screen, despite all the discussion around it. Never really had a problem with it.