I'm fairly new to video editing, lot's of experience with audio. I need to provide content to a web developer who requested H.264. I understand this is a member of the MP4 family, but am unsure what to 'render as' and which template to use for best quality etc.
H.264 (aka AVC) is available through the Sony AVC and the MainConcept AVC encoders supplied with Vegas. Either will output an h.264 .mp4 file.
As to your starting template and custom settings, it depends entirely on the source material, and the size, quality, and delivery method of your final product. If you can provide those essential details, someone here will be able to suggest some possible starting points.
In addition to the above, bear in mind two things:
1) The Mainconcept encoder does *not* set the streaming bit at the beginning of H.264 encodes, so you will need grab a separate mini-app to do the post-processing on any mp4 files you plan to post directly to the web, and expect for folks to stream them (or play them through progressive download). My recommendation is to use rndware's MetaData Mover - http://rndware.info/products/metadata-mover.html
2) If you plan to push the file to a streaming site (such as Vimeo or YouTube) *your* specific output encode parameters matter less, but you'll have to look at their recommendations for files (data rates, sizes, etc) they're willing to upload and transcode for playback from their site.