Server Audit

Here is the result of a server audit, which concerns me, but I'm not sure how to fix it.

PHP: 

• PHP accelerator  =   - WARNING (The script can be much faster if you install some PHP accelerator)
• PHP setup  = cgi-fcgi  - OK 

MySQL: 

• key_buffer_size  = 805306368  - OK 
• query_cache_limit  = 1048576  - OK 
• query_cache_size  = 0  - FAIL (must be >= 16777216)
• query_cache_type  = OFF  - FAIL (must be strcasecmp on)
• max_heap_table_size  = 16777216  - OK 
• tmp_table_size  = 16777216  - OK 
• thread_cache_size   = 384  - OK 

I will have to contact my server support to change the failed MySQL issues. Should I request that they change the query_cache_size to 16777216? Or do I want this to be much greater so it can increase with the size of my site? 

Web-server: 

• User-side caching for static content  - click here to check it in Google Page Speed
  If it is not enabled then please consider implementing this optimization, since it will improve perceived site speed and save the bandwidth, refer to this tutorial on how to do this.
  To apply this optimization you need to have expires_module - Array
• Server-side content compression  - can be checked manually or in "Page Speed" tool build-in into browser.
  If it is not enabled then please consider implementing this optimization, since it will improve perceived site speed and save the bandwidth, refer to this tutorial on how to do this.
  To apply this optimization you need to have deflate_module - Array

UNA: 

• DB cache  = On (File based cache engine)  - WARNING (installing PHP accelerator will speed-up file cache)
• Pages cache  = On (File based cache engine)  - WARNING (installing PHP accelerator will speed-up file cache)
• Page blocks cache  = On (File based cache engine)  - WARNING (installing PHP accelerator will speed-up file cache)
• Templates Cache  = On (FileHtml based cache engine)  - OK 
• CSS files cache  = On  - OK 
• JS files cache  = On  - OK 
• Compression for CSS/JS cache  = On  - OK 

It seems to be warning me that installing a PHP accelerator will speed-up file cache, so is that something I shouldn't do or something I should do? If I should do it, warning me about it might not be the appropriate word, perhaps the word "Attention" would alert me to the idea without making me think I'm being warned against it. Warning implies risk or danger.