As a resident of Boston, here are some suggestions.
1) The tournament venue is pretty close to the Kendall Square T stop on the red line. It's easy walking distance at about a quarter mile away. If you can get to this T stop, then you'll be all set. By the way, the "T" is what we call the MBTA rapid transit system (subway).
2) Driving and parking in Boston sucks. I would recommend staying somewhere that is T accessible, and taking the T to Kendall. However, there is a parking garage near Kendall Sq. Not sure what the weekend day rates are, but I'm sure it's reasonable. There is metered street parking, but you would have to move your car every two hours to avoid tickets.
3) If you stay outside of Boston, one option is to drive into the Alewife T station at the northern end of the red line. There is a large parking garage there that costs $6 for the day, I think. Kendall is just a ride down the red line from there.
4) Lastly, if money is no object... there is a Marriott hotel right at Kendall Square. Very convenient, some of the rooms have a river view, but certainly will be a bit pricey.