I have existing system which provide poducts and prices. I need connect this system (rest api) with magento. Can magento do think like this? Or is good idea doing this?
Yes, Magento supports REST API,
Magento is connect with any third party service using API of magento.
You can sync your System with Magento.
Kindly check below links for magento 1,
Yes, magento supports Soap and REST APIS. you can use default methods and can develop your own as well.
Here you can find more information about SOAP:
Here you can find more information about Rest:
Please let me know if you have any questions.
If i have answered your query then please accept/kudos my answer.
If i want to display custom collection using REST then can we do that? How can i develop ouwn custom REST method?