Hi George,
a rather mixed bag of questions but many that all people should ask before investing in a foreign country.
Yes, Altinkum is a very good place to purchase, but, one of the 'Hot Spots'? If you listen to any agent they all claim that the area they are in is a'Hot Spot'.
Property increases in value are becoming a little hard to predict, there are in some areas a surplus of properties for sale both new & re-sale so you really need to do your homework before purchasing.
Rental yeilds are very different in each area, a lot will depend on the type of property and very important, the local amenities, and, to whom you wish to let the property.
I have friends & clients, some of whom are very successful in letting their property & some who are not, an example of the extremes is one friend who has rentals for his 6 bedroom villa at £900 for 40 weeks next year, mainly repeat business,and, another friend who rents his apartment for between 15 & 20 weeks a year for on average £250 pounds per week, I do know of many others who do well on renting for friends & familly, and, a few who are not having any luck at all. Obviously marketing the property is very important.
Dont go down the road of Guaranteed Rentals from your agent, you dont get anything for nothing in this world.
In my area we may be lucky with Easy Jet coming to Dalaman from the end of March this year.
Also in my area there is a huge market for rental of cheaper properties for the workers who come for the season from other Turkish cities although on average the rentals are approx' 500YTL per month some lasting from April to November.
Experience has shown that now the market has slowed a little in most area's profits will be under what a lot of the pundits predict.
Yes a property in Turkey will be a good long term investment especially that at the moment there is no capital gains to be paid here after you have owned a property for 5 years.

Good luck with your intententions.
CJ.