You can exchange lr to paypal and then buy domains anywhere. There are some sites that do so. Or try moniker.com. I think they accept many payment modes...
Do you mean which is a better name - a 4 letter .org or a 4 letter .net?
well, if ur website content is related to an organization(maybe a non profit one), then a .org is better. But if ur looking at commercial website content then .net is better and more popular.