You didn't identify the specific model of Buell so can't make a specific reply, however, almost always, you are best off to replace with the TYPE of tire that came O.E. on the bike because the fork spring rates, shock dampening rates, etc. are based on the tire characteristics and weight. i.e. the tires are part of the over all suspension design. Radials and bias ply tires can have fairly significant compliance differences because of the different internal construction and cord layout, etc., thus possibly affecting handling. Check you Owner's Manual and/or with a dealer.
(I assume H-D dealer still service Buell and have service info.)
Yes....you are far better off by having a proper balance job done on the new tires. Out of balance tires can be annoying (shaking or vibration at speed) and can also develop irregular wear problems. Not a good place to cut corners. If you are going to get new tires, do it right. Also, be sure to replace the valve stems if you have tubless tires. They don't wear out, but the rubber hardens over time increasing the probability of a leak between the stem rubber and the wheel. CHEAP insurance, especially on a motorcycle.