Solid Hardwood, Engineered and Laminate Flooring - Carpet-to-Laminate conversion

I'm planning to rip out my carpet in the living room and install laminate floor. After I rip out the carpet, how smooth does a plywood underneath have to be?? Can I pour in self-leveler or nail in the brand new underlayment board instead of pulling out all staples and spend lots of time with clean-up??

I'm thinking about using UNILOC laminate planks. Can anyone recommend good & affordable brand?? I don't have a large budget, and house isn't a brand new house; so I'm looking for decent product with impressive price tag.
Thanks in advance.

Your house may be older but it has a value that far exceeds the difference of the cheapest and the best laminate flooring. Find a color and pattern that works with your decor and then negotiate or find the "best price" for the best product, the one that looks best in your home. Enhance the value your property and keep in mind that to get your money "out" of the property you must sell it. Sell it well, not to a buyer looking for an impressive price tag. The sub floor must be sound and flat for a proper floating floor installation. Flat is more important than level. Using a new sub floor or pouring a self leveling product will both raise your floor and doorways and or appliances may be effected. If the floor is flat within the requirements of the flooring manufacturer of the brand of your choice, the staples and nails will be easy, either pull or pound, it won;t take long. Good Luck with your project

Yeah...the floor has to be in great shape without any signs or cracks or warps (if there is some damages there, then it has to be replaced by SAME thickness of plywood, otherwise the floor won't be even)....and also to make sure that the floor is securely nailed down...as if there are some loose spots, I would suggest to use "gripper" nails (the ones that has some rings on the body of nail) or drywall screw to screw it down permanently....as I had also saw that the fancy, custom, or expensive homes that use some type of drywall/deck screws to secure the floor plywood down....in other words, no way of getting squeaks, etc...

I might be right or wrong...but I like the idea of using either "ribbed" nails or drywall screws....

Rick