Well the offer is not bad even not very good for a position of a "Recruitment Manager". You should try to negotiate for more due to inflation. If they don't then take it.

Secondly, I don't know why they are calling you on a business visa ? Why they cannot issue Resident Permit for you and your family directly ? I don't advise you to come on a business visa since you will have no rights if Company terminates your services before applying your Residence Permit.

If you land in Doha on a RP then you will have all the rights for your Employment in Doha as per QLL.

Also you will find Qatar Labour Law here: http://www.qatarembassy.net/Qatar_Labour_Law.asp

All the best.