Does a tube amp's wattage needs to match or be close to the speaker or speaker's power handling ?  Can a small amp push high wattage speakers or a large 4X12?

All that is required of speaker cabinet is that it has enough power handling for any given amplifier. Any low wattage amp can push a speaker cabinet despite high wattage ratings.   Guitar amp speakers have sensitivity ratings of about 95 db to 101 db.  This means speaker will produce 95 to 101 db with just one watt of power at one meter of distance!  That is very loud!!

 Wattage and volume is not a linear relationship. To be twice as loud an amp must have 10 times the power.  So, a 5-Watt amp is half as loud as 50-Watt amp with all things equal (they rarely are though).  A small amp will be more than powerful enough to get any cone moving.

 Whether or not you like the feel and/or sound of high wattage speakers is subjective.   Higher wattage speakers have less cone breakup and different distorting characteristics: They tend to be cleaner and typically have more lows and smoother highs.  The speaker parts themselves often are stiffer and have more mass so high wattage speaker tends to be less touch sensitive but also clearer and firmer sounding. Some companies have spent lot of time designing high wattage speakers that react and play far more like their low wattage counterparts. Eminence is good example of such a company.

Putting a low wattage amp through large speaker can sound great so do not be afraid to experiment!