If you are talking about pets, no there is no limitation, they would love for you to have as many as possible. For money, there may be, however it isn't until a very large number, because I know there are millionaires in Webkinz.
It cost the same amount as any other Webkinz
Your Webkinz Username has nothing to do with the amount of money you get when you start/adopt a new Webkinz. The money you get comes with the amount of Webkinz you have. If you're just starting Webkinz or get a new account, you receive $2000. If you have 2-9 Webkinz Pets, each time you adopt another you get $2500. When you adopt a tenth Webkinz Pet, you still get $2500, but you get a super bed of your choice, too. You can get another super bed after every 5th pet after 10. Adopt more than 10 Webkinz pets and you get $3500 dollars :)
You are only limited to a certain amount of powers.
Webkinz get retired because not a lot of people buy them in a certain amount of time. Some Webkinz get retired when they first come out.
You can never guess, you have to wait a certain amount of time.
A LittleKinz is known as a Webkinz junior is a same thing as a Webkinz but just smaller. In my opinion, LttleKinz are better than Webkinz because it is the same thing but just smaller and cheaper. You also get the same amount of money when you join Webkinz world, 2000 kinzcoins.
Solar power is of course limited by the amount of solar radiation that reaches an area. If the weather is overcast or the sun is occluded, the amount of power that is able to be generated is limited.
Webkinz cares is a program to show that you care about your Webkinz. Every time you are on you go there and click the button. It will give you a small amount of Kinzpoints and one meal. If you do it every day from Monday to Sunday, you might get a exclusive item.
There's no set amount of time. You get get a Webkinz eStore account as soon as making a regular account for Webkinz. Just go to their website and make an account there. It will be linked with your playing account, so any points or items you buy, will be on your playing account.
SALT was an acronym for Strategic Arms Limitation Talks.
There is no exact amount that anyone can give, but probably thousands and thousands of members.
They have a very short amount of time to gain any useful information