Blocks (.dwg) to Microstation cell library (.cel)

In the Cell Dialog of MicroStation you can attach a folder (containing the dwgs) then you can just Place Cell from the dialog. No conversion required.

but won't the colours and weights and linsetyles be all wrong for microstation

Sometimes true, MicroStation is really kind of "translating" the colors right. But sometimes getting it wrong. That mght require a batch conversion with Remappring (SaveAs ... [Options]) Weights and LineStyles can be a challenge as well. 

But if you are lucky ... 

I was a Microstation customization workspace, where I insert cells from ribbon button.
Both before and after cell placing I require certain condition which I wrote in VBA.
So I through get cells from cell library will be beneficial when I deploy to the users.

Do you have any other workaround for same?

Since a cell library is simply a DGN format file with many models (each of which is a cell) you may be able to convert all of your DWGs to DGNs, then Import each of those models into a single cell library.

That may be something best handled by a combination of Batch Converter (to change file format) and VBA (to import and rename the default model of each created DGN. There's a Programming forum where they could help you refine any code you write - just make sure to tell them which version of MicroStation you are using because capabilities and bug vary by version. Nobody there can write the code for you, but they can help you figure out calls, methods and procedures.