1. You should consider checking system requirements
to make sure that the backup infrastructure can withstand such load.
2. That depends. If they have simliar RTO and RPO and contain comparable data then it's a good idea to keep them in one job for a better dedup ratio.
<...> but when one of the sql server has log issues i have to run a full backup to fix the issue,
Could you provide more details on that please?
2b. Please check system requirements for that.