Should I put some gravel on the bottom of the pots for drainage.
No gravel, it's a waste of valuble space; same with broken pots, I wouldn't use more than 1 piece over the drain hole if it's a large hole. Just use a good compost on the bottom--the roots will seek it out for nourishment.
I get compost from a municipal compost facility in the suburbs, they dump a big load nearly filling a pickup truck to the top for around $18. It's much more economical than trying to buy bagged compost. Or they fill a garbage can full of compost for $2.50 to $3.00.
For the 5 gallon buckets, I add about an inch in the bottom, then mix about 50% pro-mix and 50% compost together and fill the remainder. If you are not 100% organic, your best bet is to add a time released fertilizer like Osmocote 14-14-14 or Walmart's own brand, I think 17-17-17. The last couple years I even used Miracle-Gro Shake N Feed for Roses, I think that was around 9-18-9. Higher middle #s have more phosphorus, which increases blooming and hence fruits. It also promotes strong roots.
If you use drip irrigation, or even a hose end fertilizer sprayer with a water soluble fertilizer, I start the season with a hi-phosphorus (middle number) fertilizer, like 10-52-8 for the first month to get strong roots and more blooms, then switch to a more balanced fertilizer like Miracle-Gro for Tomatoes 18-19-21, Peters 20-20-20, or Plantex 15-15-18 soilless for potted plants after fruit set. If you can't find any 10-52-8 (or 10-52-10 or similar #) you can use miracle-gro bloom booster (15-30-15.) Just don't use anything with a high first #.
Growing organically is tougher in containers because you get much less bang from the fertilizers. I'd recommend Neptune's Harvest 2-4-1 Fish & Seaweed fertilizer. Things like Bonemeal are great for calcium and may help prevent Blossom End Rot (BER), but in containers, they usually wash organic nutrients out the bottom before they have time to break down and work. Use lots of compost and add some cow manure too. Both are usually under 1-1-1 NPK (N=nitrogen, P=phosphorus, K=potassium.) For K, use your wood ashes!
Your climate is probably similar to mine, summers 80-90 high and 60-65 lo temps. I water daily.
Hope this helps.