Database: MySQL optimization on a dedicated server

There are some documents on this subject, but it does not cover my use case:

I have a new server running Ubuntu 18.04 and I use it only to run MySQL (another tower is running apache / Drupal / PHP / …)

This "MySQL tower" has 48 GB of RAM and a single SSD.

There are 19 websites / databases (most are small sites with little traffic)

Total database size = 8 GB (the 3 largest databases have 1.7 GB each)

Question 1: Is it 100% safe to say that I should switch to InnoDB?

Question 2: What values ​​should I use for the following MySQL parameters?: (Below are the default values ​​after installation)

key_buffer_size         = 16M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
#max_connections        = 100
#table_open_cache       = 64
#thread_concurrency     = 10
query_cache_limit       = 1M
query_cache_size        = 16M

Question 3: Is there anything else to do?