with your lighting you can do 4 to 2' but it will take awhile, I started out with my first grow with 2 dual bulb 4' flo lights from lowes had about $30 in it total I did 8 plants 3 was males 1 was a hermie, and 4 ladys, I did end up switching to a 400w mh for veg and 400w hps for flowering, also relize they will stunt alil if you decide to switch later my stunted for about 1-2 weeks then they took off like rockets under the new lights, I'll never go back to florecent lights. you also don't have to go big on lights either you can get like a 150w hps or mh on amazon for around $75-80 also if your just doing mother plants and not budding them I wouldn't use a 5 gallon bucket use something like a 10" pot to save you some space they are around $3 each at walmart.
also topping will not help with getting clones, ppl top to more or less get 2 main buds at the top.
also depending on how many plants you got 2' plants will not produce alot of clones, might wanna look at vegging a few girls for a few months under your lighting or better lighting might take longer but try getting them bigger if you want more clones and remember you can veg one for a long long time just dont ever switch it to 12/12. also make sure you sex your plants before you do anything with the clones todo that switch your lighting to 12/12 for 3-5 days til they start to show then switch back to 18/6.