Hey bluebottle87
Sorry for the delay in me getting back to you - I've been away from the office for a few days.
There is a huge amount of info on this thread on nipple piercings and aftercare - http://www.lovehoney.co.uk/community/forums/off-topic/778924-nipple-piercings/
As long as you follow the instructions here, you really won't need to worry about infection. Just keep it clean, without overcleaning, and don't fiddle with it!
A nipple piercing for a man is a little different than for a woman, purely because the nipple is a different shape and size. Everyone (male or female) will respond differently to a piercing, and could become more or less sensitive after being pierced. My ex had both of his pierced and he said that they were more sensitive after they were pierced, whereas other friends of mine say they notice no difference at all.
For a man the piercing goes a litte deeper, going through the Areola (the dark circle around your nipple) as opposed to through the actual nipple itself (simply because mens' nipples are usually smaller than womens'). As a result the bar sits just behind the nipple, making it less likely to catch on clothing etc. It can mean it's a bit sensitive for a while (whilst it heals) but this settles with time.
Always get pierced with a straight bar and follow the instructions in the other thread for cleaning etc. Aftercare is exactly the same for all nipple piercings. Also, ensure that your body piercer uses a sterile needle to pierce and uses sterilised titanium for the jewellery. (Bioplast, Blackline and TPFE are also acceptable, but Stainless Steel, Gold and Silver is NOT suitable for a new piercing and is more likely to give you problems)
One more note to add - don't compare your ear piercing to a nipple piercing. I would hazzard a guess that you had your ear done with a gun rather than a needle? Which probably means the jewellery was a butterfly back stud made from gold or silver - see this article to see why this is a problem for a piercing. If it had been pierced with a needle and jewellery as above, chances are with proper aftercare your ear would have healed with no problems :)
The APP (Association of Professional Piercers) is also full of a plethora of info on all piercings, but if you want to know more about guns vs the needle, check this link out.
Any other questions, please feel free to ask away!