Hi Steve,
Q1: Would it be a lot more work? Apart from the feeding etc.
Answer: I would totally recommend getting two kittens (preferably litter mates). It is more more work just the costs obviously increases as there will be 2 lots of injections / spaying / neutering / etc. Also with 2 kittens they can entertain each other and keep each other company when you are out.
Q2: When buying two kittens from the same clan, would there ever be a time when they would suddenly take a dislike to each other that cannot be resolved? and would they need to be integerated with each other? (i think not because they'v got a bond i would imagine)
Answer: If you get litter mates there is a strong chance they will be friends for life and there is no reason why they should turn against each other as they get older.
With regards to the cats in the garden .... I would just leave things as they are. Once your little ones are old enough to venture out doors (once they have been fully vaccinated and spayed/neutered) they will soon claim your garden as there own. As it is coming upto winter I would recommend keeping your babies in as long as possible before letting them out (at least until they are 6 months old). The longer they stay indoors the better.
Q. Are cats like most other animals, where their sex determines how they are? For instance, a females more smellier than males? Are females more aloof? males more friendly? etc
Males are usually larger than females. Some femals are aloof / but then so are some males. Males are more inclined to roam even when they have been neutered (it's a boy thing!
) but of course as with all animals (and people) it's very hard to stereo-type. For every wandering male someone on this forum will have a wandering female ... likewise for every super friendly male we can find a super friendly female. Basically they all have their own personalities.
Hope this helps and good luck in your kitten hunt.
Sam