Hi and welcome to the forums
I can't see that traffic level being a problem. You should be fine on any of the DreamHost shared plans, unless you have an errant script that consumes too many resources and degrades server performance.
There aren't any hard limits on resource usage here at DreamHost, other than the storage and bandwidth restrictions imposed by your particular plan. Generally, if you are not adversely affecting other sites on your shared server you will be fine.
I am not familiar with SMF, but a quick look at their website shows that its requirements are simply PHP>4.1.0 & MySQL>3.23.4, so it shouldn't pose any problems here.
As for the 'special features'; There is pspell support in the default DreamHost PHP install, but I am not sure about APC (see the link provided by Affiliate7 below);
The DreamHost PHP system is particulary versatile. You can use the default DreamHost PHP install, and this will be adequate for most things, however you can also install a local version of PHP into your home directory and configure your sites to use this instead of the default install. This allows you to change various configuration options that may be required for your site.
Edit: Added 'stuff'
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