http://www.mdbg.net/chindict/chindict.php?page=worddict&wdrst=0&wdqb=dian3 This dictionary site is pretty convenient because you can type "dian3" and it will return all the third tone "dian." Beyond that, I'd say it's not very efficient to learn words by memorizing each possibility for each tone of a syllable. The obvious example would be shi4 which has dozens of meanings, and over a hundred if you remove the tone.

点（dian3） in chinese dictornary it means1. touch lightly as with finger, brush or rod 2. drop,spot 3. tiny amount；a little；o'clock； For example : 点餐（order the meanl），use the dirst meaning cause you needto use your finger to point the name of the male to the waiter or waitress. 雨点（raindrop），use the second meaning cause the rain will become a tiny drop after it fallen down. 一点点（a little）,use the third meaning. PS:it means "O' clock" cause the "hands of the clock" point somewhere or somenumber then you read the time,so we use "dian3" to describe time.

main ones: o'clock, order, dot, a little, feature

Yes it has many meanings. It can also mean "dots". It will be very difficult try to memorize all different means in this way. It would be better if you choose some sentences to see how the word works in different conversations and then summarize them all.

點 : 名詞 : 計時的單位。一個小時稱為「一點」。如：「中午十二點」。 動詞 : 指定。如：「點菜」、「點歌」、「點播節目」。