2. Yes, up to the legal team and what types of processing you do. If you do processing that the data subject would not expect you to do or that is not in their interest you have to consider this carefully. Maybe allowed or not under legitimate interest but you have to be careful and do a proper assessment. I believe, and I have heard many EU data protection lawyers state, that consent is a last resort option. Probably not universally shared but many ppl appears to think in that way. Also, remember that consent bypasses important principles, such as the necessity test present for all other legal basis.
3. I agree, both RTBF and SAR rights under legitimate interest but no absolute requirement to automate the process in any case. Implementing voluntarily data portability good practice which could tip the balance when using legitimate interest, see below.
4. Yes, and concerning legitimate interest, if you implement these best practice measures this could “tip the balance” in your favor if you read the WP29 legitimate interest opinion.