spay n neutral dilemma

Question
hi there. i have a problem with my two persian cats. one female (4 months) and one male (6 months). i am torn between the decision whether to get them fixed or not. but i would really like to have their kittens. my questions:

1) can i get them fixed after the 1st pregnancy?
2) can i just spay my female cat ONLY?
3) if the answer is yes to my 2nd question, can they still  mate? i dont want my male cat to behave badly (like pee all over the house,etc) after the spaying of my female cat. will my female cat let him?
4) how to tell if a cat is in heat?
5) also, i find the idea of spaying n neutralizing to be cruel, against the nature n unkind to the cats. i cant bring myself to do that. is there anything i can do to or medication that can help to minimize their sexual interactions if i were to decide not to get them fixed?

please! guide me out of this misery. thanks a million!  

Answer
You can have a cat fixed after the 1st pregnancy.  She will need to wait 10-21 days after she has weaned the kittens, until she is no longer producing milk.  Problem is, she can become pregnant during this time, so you'll need to separate the cats.

Answers 2 and 3 I addressed just a moment ago in a question you had sent separately.

Signs a cat is in heat are rolling around on the floor, chirping, howling, raising her rear end, and sometimes urine marking.

I think it's important to realize that a cat's sexuality is not as involved as a human's.  There is no emotional bond between cats through mating.  There is no thought process where they decide they want to have kittens.  Mating is driven strictly by hormones.  They don't know why they do it - it's just instinct.  Removing the source of these hormones and the source of this instinct doesn't effect them negatively in any way.  If anything, it makes them happier.  It takes away the constant preoccupation they have with mating.  This relentless desire can become exhausting.  A cat becomes so obsessed with mating that it will often lose appetite.  Additionally, a cat who isn't spayed is highly likely to develop mammary cancer or a deadly infection of the uterus called pyometra.  

You can suppress the hormones that cause a sex drive with a drug called megestrol acetate prescribed by a vet.  Unfortunately, this drug causes a huge risk of diabetes and mammary cancer in both males and females, even if used short-term.  If you are trying to minimize mating, then neutering and spaying are definitely the way to go.  The surgeries are tolerated very well.  Most males are themselves the next day, and females are back to normal in a few days.