There are so many tight places and hose clamps. I use this tool constantly when monkeying around with the car. It is a godsend when you try to replace the PCVs.
As far as getting the stuck hoses off, what the others said plus one more tip: try to spray just a teeny bit of WD-40 (using the thin red tube) at the end of the hose where it meets the nipple. Hopefully some will seep in between the hose and the nipple and lubricate it. But if you spray too much you will get WD-40 everywhere and compound your problem. Lube the hoses with a bit of oil to make them easier to get off next time.