Life metrics for v-brake pads (time to replace, time to change) I ride my bikes quite frequently and need to use the brakes slightly harshly (because of the traffic light changes and cars at my front) as I approach some gradients worth 40 degrees downhill. My regular commute culminates to approximately 4 miles (with gradients and 5 days a week) and 0.25 miles (with gradients and 2 days a week). I have used simple tuning to maintain the v-brake positions along my front and rear rims and cable tensions for the brake cable (by adjusting the nuts near the brake levers). However, it seems that they don't stay put for more than a month or two. Additionally, I noticed this morning that my rear brake pads are almost worn out (broken and cracked edges). My question is, how do I determine how often the brake pads needs replacements? It would be fantastic if someone points suggests any side-effects such as brake cable wire damages and replacements etc.

Also, I recently puchased this set of pads with housings. Does anyone know if it is any good? My current brake pads are naked i.e. without any housings.

Thanks a lot!
It's difficult to give a general estimate on how often brake pads should be replaced, as conditions vary. (Including how often you ride, temperature, humidity, do you store your bike in direct sunlight, how old the brakes are, etc.) If it looks worn, replace it.

Adjusting brake tension via the screw nuts on the handlebars is the best way to make adjustments. As brakes wear down with use, you will need to make these adjustments to compensate. Needing to do this ever month or two seems within the normal range for how often you use your bike. 

Another factor to keep in mind is that cables will stretch with use. If the screw nuts on the handlebars are at their limit, you will need to loosen the nut holding the cable at the brake to adjust the cable. (When you make this adjustment, make sure to reset the screw nuts on the handlebar).

Your recently purchased brake pads seem fine. I've found that a manufacture will include the housing even if it's not needed. Just be sure to toe-in your brakes slightly, and reset the handlebar screw nuts (and cables) as needed.