Quick-fire CV questions (UK)

Following the M&I template [here if you don't already know it]. CV will be for IB/Consulting. Simple questions with hopefully simple enough answers: 

1. Pre-university education (A levels): Takes up too many lines, opinions on putting "A/AS-Levels: X, Y, Z, ..." as an entry under Skills, Activities & Interests?
2. Including MS Office / Excel as a skill: I've already put some Excel certifications in the relevant section to be more subtle, but see some others on this forum putting "Skills: Microsoft Office, Excel, ..." in direct contradiction to most advice. Thoughts?
3. Including AI as a skill: Eye-wateringly cliche, but seemingly increasingly popular. Yes/No?
4. Had to take medical leave for a few months in the middle of my degree, so it shows as 4 years since I had to rejoin the next cohort the following semester. How would you clarify that cleanly? M&I kind of implies you can just put your graduation date instead of [Start - Finish] format, but I'm not sure...

Ty