What do I do when cutting the flexible strip?
The strip can be cut ONCE, there are marks on the strip which show where it can be cut (25mm intervals). When you cut the strip the cut end must be sealed with an end cap (SE300050) and silicone for the strip to retain its IP integrity.
If I cut the flexible strip will the wattage remain the same?
No, the wattage of the strip would be reduced by how much is cut off (how many LED's). For example if a 2m strip has a wattage of 15W and 1m is cut off the wattage of the 2m strip will reduce to 7.5W.