If I have 51% of the capacity of the entire network, can I mine absolutely all the blocks faster than the network? I'm really wondering can I mine absolutely all the blocks in the network faster than rest miners with their 49% hashing power not for the purpose of conducting double-spend attack?
Can you mine absolutely? No. If you have 51% share of the network hash rate then the probability (not certainty) that you will mine the next block is 51%. It is theoretically possible that you may never find a solution to the block ever. However, if you continue to mine on the blocks that only you generate, then practically you can build a chain that consists entirely of the blocks that you mine after the forking point.