Connecting a second router to act as a separate/2nd wireless access point is quite possible but your whole network would only be as secure as it`s weakest point as far as the wireless connections are concerned. You would still only have one network, albeit with 2 means of connecting wirelessly, and not two different networks.
I mentioned recently that i currently use 2 routers myself although only one acts a Wireless Access point. I have had both doing wireless in the past though and i have had both using either the same wireless settings or indeed completely different wireless settings, never completely Open though.
Our own 2nd router/access point gets it`s net directly from a machine on this side of the house, rather than from the main router itself, but the principle is the same either way. Just remember and use LAN port to LAN port when connecting the 2 routers and make sure the DHCP on the 2nd one is turned off and it has a different IP range to the first. Also look for any router/gateway type options that your particular models might have that need changing but you seemed like you were on the right track to me.
As has already been alluded to you have to decide what the chances of somebody trying to hack your wireless connection is in the first place. If you live out in the sticks with not another house within miles then the chances are pretty slim but if you`re in a built up area with dozens of other neighbours then the chances are probably a little less slimmer, although still quite slim all the same i`d say, with
at least WEP anyway.
Using a completly Open connection is just inviting all & sundry onto your network though and not something i`d ever do myself.....not unless i was
really bored.