My WBJEE rank is 4503. I want a BTech in CSE. Can I get into Heritage Institute of Technology? What are some other government/private colleges for BTech CSE at this rank?

Both the choices are decent so you can choose either. But, as I don't know exactly which branch of DSU are you asking about; but if you are talking about DSU (Kumar swami layout) then go for it; and if not NHCE is better.

• If you are hard-working go for DSU as placements for CSE and ISE are the same and you should prepare for the campus placements as well. In DSU the average and highest CTC offered is 4 LPA and 15 LPA. 
• If you are an average student in CSE, then NHCE offers 100% placements for CSE. In recent years the average CTC offered at the institute is 3 LPA. 
• If you are going to an engineering college in search of a decent job then go for NHCE.

And let me clear that, 100% placements mean there are no specifications of package you will be given. You might get a company to work with a 1 LPA salary or a 12 LPA salary depends on your caliber and knowledge.