It always depends what you want. I understand that you just want to express your GOI in a eukaryotic cell. The most popular vector is pCDNA3 but there are many vectors around with viral and cellular promoter/enhancer elements. You should also consider fusion proteins, e.g. with EGFP. There is an example a whole series of pEGFP plasmids from Clontech.
Concerning your second question. It makes sense to use a mammalian cell line and you have to decide whether it is important to use a human cell line. In addition you should consider whether you want a cell line where the endogenous gene is expressed.