How much should I practice?

30 minutes a day is ideal, but sometimes not possible.  We all have a life.  You can't always be practicing!  Essentially you need to practice as long as it takes to get it right.  Sometimes that means 10 minutes, sometimes an hour.  I rather you practice 10 minutes every day rather than 60 minutes right before your lesson.  Remember slow and steady wins the race!  You can't "cram" your practice-you won't retain it and you end up making dumb mistakes because you are overtired.  Runners don't wake up the day of the marathon and expect to win.  They train for months.  Same concept.

Should I rent or buy?

If you are a beginner I recommend renting.  Once you have determined you like playing and are making progress you can purchase if you want.  Most music stores have a rent to own option.  Often the instruments music stores rent are high quality instruments.  Be wary of flutes that are very inexpensive.  Often these flutes are made by "no name" companies with non-uniform parts that are difficult if not impossible to replace or repair.

Will I be able to play the flute easily?

Maybe!  If you are able to blow across a bottle top and make it sing, you will most likely be able to make a sound on the flute quickly.  But don't worry if you can't.  With practice and patience  you will eventually be able to make a sound.  Now making different notes....that is different.  As long as you have 10 fingers you can play a "traditional" flute that has lots of keys. With practice, patience, and some coordination you will be able to play different notes.  For some, playing an instrument is as natural as breathing, for the rest of us it takes some focused practice.