I'm not sure why they would charge him with both a felony and a misdemeanor violation of PC 459 - burglary.
It depends on where you're seeing both the felony and the misdemeanor listed that may matter.
Either way - he's facing burglary charges. What we don't know is whether it's first degree (residential) or second degree (all others). If it's first degree, it's a straight felony and cannot be reduced to a misdemeanor. It's also a strike under the 3 strikes law. If convicted of first degree burglary, he is also presumed to be ineligible for probation, although a court can grant it. The maximum on first degree burglary is 6 years state prison.
If it's second degree, that's a "wobbler" and can be either a felony or a misdemeanor. As a felony, the max is 3 years state prison and as a misdemeanor, it's a max of one year in county jail.
Without knowing anything else about the case and not even being 100% sure what the exact charges he faces is, that's the best information I can provide. From here, your son needs the very best criminal defense attorney he can find that routinely practices in the court where his case will be heard.
Mr. Dane has very cogently outlined the general law of burglary. The "remand/rearrest" language probably means that he is in custody for one offense and is being remanded and rearrested for another. So, hazarding wild guess -- could it be that he went to court on a misdemeanor burglary and the judge sent him back to the jail with a remand saying "remand/rearrest?" This could happen if the original charge was being dismissed in favor of a new, more serious, charge.
However, I am not sure of this at all -- we need much more information. But, more importantly, as Mr. Dane suggests, this is a very serious charge and your son should have the services of the best lawyer you can find. If he cannot afford a lawyer, he can apply for the services of the Public Defender. His lawyer will be able to determine what the exact charges are and what the circumstances of his custody are.
If you are writing because you are thinking of bailing him out, then (besides calling the lawyer) you can call a bailbondsman. The bondsman (man or woman) will be able to determine exactly why he is in custody and what it will take to get him out.