Just got a new SP4 and have some questions

Hey guys. Just got my new SP4 and loving it so far! Just have a few questions about it:

1. Is it a good idea to buy a screen protector and a case? If so, where from (I live in Australia)?

2. Likewise, since the battery is a bit average, what would be a good batter/power pack to get? I'm thinking of the Mi Power Bank but not sure if I could get a USB to power outlet adapter.

3. Any recommendations on software, settings, tips to maximise usage, etc? I've heard of adblock for Edge and lowering the maximum CPU frequency but not really sure on it.

4. I'm very likely going to dual boot my SP4 (if possible) with Remix OS. I like tinkering with tech and I like having a variety of options; and there are some really useful apps and services on Android. Any guides or advice? I found this, but not sure whether it would work on SP4 or not.

Any answers would be appreciated. Loving the overall experience so far, especially the pen. I've got high hopes for the SP5 and 6 - longer battery life would really make this device shine!