Caviar Swap is a pool-based centralised Automated Market Maker (AMM) on the Radix L1 Protocol
No since smart contracts are not live yet on Radix. It is a centralised service hosted on our servers which uses similar bonding curves to Uniswap / Sushiswap / Balancer.
A bonding curve is a function of the balances in a pool that determines how much of token B you get in return for sending in token A - in essence it determines the exchange rate
Caviar Swap currently uses a geometric mean bonding curve (akin to Balancer) with equal weights. This is equivalent to a constant product across all balances in the pool
This will be enabled once smart contracts are live. However you can consider starting your own pool using our Caviar Pools service