PACs don't support a boolean data type, but using an Int32 for just one bit isn't such a big deal since you have lots of memory (see this tech note). Also, as you pointed out, using Mode = 0, 1, 2 is a good way to solve the same thing with just one tag!
We also don't support CONST values exactly, but you could name some int32s will all caps (common naming style for a constant) and call them TANK_MODE_OFF, TANK_MODE_HAND, and TANK_MODE_AUTO with values of 0, 1, 2. Better than using 0, 1, 2 int32 literals since you can search for those "variables" later, but you can't search your strategy for 2 later if you want to figure out where you're setting that mode to TANK_MODE_AUTO, for example.
For your IDC5-FAST, just let the brain part of your R1 do the totalizing. All you have to do is in your strategy is configure the point as a On- or Off- totalizer:
Then use this command to get the value from the brain: GetOnTimeTotalizer(From Point[B])
[/B]Hope that helps!