"Is he (issuing a) warning?" is a literal English equivalent of the French phrase Met-il en garde? The pronunciation of the present indicative in the third person masculine singular will be "mey-tee-law gard" in French.
"On guard!" in English is en garde! in French.
En garde in French means "on (your) guard (because I am about to attack, in fencing)" in English.
"But take care, I'm telling you!" is an English equivalent of the French phrase Mais garde, dis donc! The statement translates literally as "But look out, I say therefore!" in English. The pronunciation will be "dee donk" in French.
"On guard! Touched!" is a literal English equivalent of the French phrase En garde! Touché! The phrases most famously reference a fencing scenario in which one fencer warns the other to beware and then realizes physical contact through a fencing move. The pronunciation will be "aw gard too-shey" in French.
In French, "guard" is translated as "gardien" for a male guard and "gardienne" for a female guard.
Salut: The word is french, but in english it is keep or hold (stay in slang usage)
en garde
It is usually pronounced as "ah-vant gard" in English. But French say it as "ah-vong gard".
Correct me if I am wrong, but I believe your are referring to the French phrase "En garde", which translates in English to "On your guard".
Forever and for always are translated the same in French: "pour toujours". A French speaker would say "je te garde pour toujours", or "je te garde pour toujours et à jamais" ('à jamais' meaning he will never give up), the latter being a little emphatic.
"beaucoup de babysitting" or " beaucoup de garde d'enfants" if you want to avoid the English term
une garde