GoChain is just another Ethereum network. There are many Ethereum networks out there: Ubiq (https://ubiqsmart.com/) , Ellaism (https://ellaism.org/), AfterEther (https://afterether.org/) , and probably more....
The point is , there is no substantial innovation in GoChain towards scaling, i.e. towards increasing the TPS. Their source code (https://github.com/gochain-io/gochain) is a fork of Ethereum source and the EVM works exactly the same as on Ethereum's Main Net. Their , so called, "scaling solution" is to increase Block's Gas limit. The miners of Ethereum's Main Net can do this too and get the same speed up, but they voted not to do it.
I doubt that any blockchain technology will deliver smart contract engine (EVM) much faster than Ethereum right now. You can focus on performance, improve the source code and achieve 1.5x, or maybe even 2x speedup, but you are always going to be limited by hardware. If a CPU executes 3 instructions per nanosecond, you just can't make it run 6 instructions, its Physics. So, if any blockchain would it be, EOS, Cardano, or whatever , claims they achieved like 100x performance speedup on their own smart contract technology, I would ask for a proof, for real (verifiable) benchmarks. So far, they didn't provide any.
But here (with GoChain) we are talking about Ethereum itself, how can Ethereum be faster than Ethereum?
Now, for the other question, it will not be possible for Ethereum to merge with GoChain because it uses a different consensus algorithm. The genesis block is different, block hashes are different, accounts are different, so , no, it is not going to work.