php memory size?

So gang -

I tried to upload about 15 pics at about 1M/each via the regular photo add feature on gallery3. The 10 of them uploaded correctly but the last 5 errored out with an error that linked me to the size issue in the php.ini.

So that said:

1. what's a reasonable size we should set for the memory size if we want to upload 20-30 pics at a time?
2. if the gallery3 is hosted on a paid host (like hostmonster for instance), where should we set this memory size - in the .htaccess or php.ini file/

thanks!
gabstero