Varianse is an STP DMA broker, they take your order and pass it on to their liquidity pools with no markup.
There is no conflict of interest, if you win, your account will increase in size and you will place with them bigger trades with them,
Slippage is very very low or nill except during news but and increase is to be expected.
Opening an account is simple an fast, you can have your account ready in 24 hours or less. They do not cold call you when you open a demo account, they will let you test it for as long as you like untill you alone make the decision to open an account (Many brokers do not know how annoying it is to be called weekly trying to convince you to open an account).
You can deposit by bank transfer or Skrill and withdrawals are also fast, you can have your money back in 48 hours or less.
And last but not least, their personnel are really efficient and corteous.