Welcome to apc. Let me try to answer a couple of your questions here.
Ok with the DIY CO2 coz it will last till 16-30 days plus minus then remix the thing again or just readd the sugar to the mixture??
With diy, you will need to make a completely new mixture every time. On a 50 gal, I would strongly recommend having two diy bottles hooked up and stagger making new yeast/sugar mixtures every couple of weeks. The problem with diy is that it doesn't usually provide a steady amount of CO2. Having multiple bottles with staggered solutions will help this out.
As far as getting the CO2 into the tank, the diffuser you pictured can be used. I believe you said you were planning to use an hob (hang on back of tank) type of filter. If so, you can simply feed the CO2 gas line into the intake of your filter. That way the filter becomes your CO2 reactor and 'feeds' the tank CO2 enriched water.
Next.. I saw lots of Fluva or Magnum...may i know what is this? Is this the filtration system??
Yes, these are types of cannister filters. Fluval and Magnum are types of filters.
As has been mentioned, glosso does require strong light and CO2 to form a good carpet. With strong light, it is really important you have good CO2. Strong light means you have to maintain your tank's parameters, ie, fertilizer levels, in a good range. Keep that in mind.
As far as test kits, some folks don't use them, some do. For starting out, I would suggest to use them so that you can get an idea of the 'rythm' of your tank - how much nitrate and phosphates are used/produced. IMO, you should get a pH and kh test kit - this will help you determine how much CO2 you have in your water. Here's a link showing how to calculate CO2 from kh and pH: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
One more link for you to look at which is a real good introductory to keeping planted tanks: http://www.aquatic-plants.org/articl...ges/index.html
Good luck, and ask away. We have all been where you are now.