Hey Tom, I'm assuming you're referring to their Hardwood Lump charcoal, not their hardwood briquettes. I have not used Cowboy lump but I have used Royal Oak Hardwood Lump and Lazzari Mesquite Lump.
Taste: there is a slightly noticeable taste difference between any hardwood lump and Kingsford Original. The lump is a cleaner tasting burn. You may not notice it initially, but if you do several lump smokes, then return to KBB, you'll taste it. Now, will you taste the hickory or oak? Possibly. You can tell looking at the charcoal whether it is completely carbonized. If there are some pieces that are not completely carbonized, those will add some of the wood taste to your smoke. If it is completely carbonized, you'll get a cleaner tasting burn than the Kingsford.
Same amount of regular smoking woods? Yes. Only decrease it if you see a lot of incompletely carbonized pieces.
Time? Lump has inconsistently sized pieces by nature. Consequently the air spaces in lump will be more inconsistent than briquettes, offering larger surface area of the charcoal to burn. Lump burns hotter for that reason, decreasing times. I find it doesn't quite last as long as briquettes for that same reason.
Suggestion. I'll be doing a Royal Oak Lump cook this weekend as a matter of fact (pizzas in the WSM). One of the tricks I've learned is to put a single layer of briquettes in the bottom of my WSM before adding the lump. I do the same thing in my chimney. By doing so, it keeps the smaller pieces from falling through the grate or the bottom of the chimney.
Keep us posted how you like the Cowboy Lump.