>1) he hasn't actually signed anything yet, and can't until
>12:01 ET
Which is why the Mavs cap space isn't tied up since they can re-sign Dirk after they complete the Parsons signing.

>2) his cap hold is still the QO for 3 days (DAL's cap space is
>tied up , not HOU's)

Offer sheet: The player currently has an offer sheet pending; if the first year's salary of that offer sheet is greater than the QO, then the value of the first year of the offer sheet is used as the cap hold.
http://data.shamsports.com/content/pages/data/salaries/freeagentcapholds.jsp