Never done a Renault engine, but all the others with hydraulic tappets I have played with, it's merely a matter of removing the plugs and spinning it over on the starter for a bit until the oil pressure comes up and pressurises the tappets.

I'd replace all the head bolts as a matter of principle. There's nothing worse than torqueing the thing down, only to have the last one fail on you.

Again like the other gent, I dont know Renault engines, but generally to 'bleed' hydraulic tappets. They are usually just telescopic and held together with a spring steel cap.

Just pop this cap/collar off pull the tappet apart and empty out the oil.

When you restart the engine it will tap like hell for a few seconds but after this the tappets will fill and the whole engine settle down.