Hi Falon,
For Pixieset Website images:
Sharpening would be as per Damien's article on Sharpening for Web or similarly named. I have not taken the Damien's Sharpening Class so cannot comment on any additional info in that if relevant for output to web.
With my Client Galleries in Pixieset, I have been having two 'sets' for social-media sized and high-resolution. I can't quite recall at the moment with the plans and the offerings, but I have the highest quality for single and gallery downloads so clients get the specific images sizes for the sets.
I no longer host my website through Pixieset and use Squarespace. For 'Studio Management' - contracts, questionnaires, contact forms or whatever else I am using Studio Ninja.
Hope this helps.