Give an simple sqlite3 table (create table data (key PRIMARY KEY,value)) with key size 256 bytes and cost size 4096 bytes, what's the limit (disregarding disk space limits) around the most of rows within this sqlite3 table? Are their limits connected with OS (win32, linux or Mac)

Basically no real limits

see http://www.sqlite.org/limits.html for particulars

The solution you would like is right here.

Each OS you pointed out supports multiple file system types. The particular limits is going to be per-filesystem, not per-OS. It's tough in summary the constraint matrix on SO, but although some file systems impose limits on file dimensions, all major OS popcorn kernels today support personal files system with very large files.

The utmost page size an sqlite3 db is very large, 2^32768, even though this requires some configuration. I presume a catalog must specify a webpage number however the result will probably be that the OS or atmosphere limit is arrived at first.

In SQLite3 the area size is not fixed. The engine will commit just as much space when needed for every cell.

For that file limits check this out SO question:
What are the performance characteristics of sqlite with very large database files?

No limits, but essentially following a certain point the sqlite database will end up useless. PostgreSQL may be the top free database Undoubtedly for huge databases. During my situation, it's about a million rows on my small Linux 64-Bit Quad Core Dual Processor computer with 8GB RAM and Raptor hard drives. PostgreSQL is unequalled, even with a updated MySQL database. (Published this year).