For conservation of the write cycle in the SSD the best recommendation is to use it with an HDD? what size in GB on SSD do you recommend?
i have a 5400rpm notebook HDD using an SSD with it brings great performance increase?
You're GREATLY over thinking this - buy a decent make SSD, stick it in, and forget about it!. It will provide the biggest performance increase of any other simple upgrade, and reliability isn't a problem, in fact it's more likely to last longer than an HDD (which regularly fail).