with firmware 1.1.4 i have set as Universal Repeater (not cable connected)
LAN >> General Setup
(left page)
LAN-A IP Network Configuration
VigorAP Management
Enable AP Management
Enable DHCP Client
Enable Auto Provision

(right page)
DHCP Server Configuration disable

Is working perfect for me with a 2830n having BOTH units same channel,same SSID,same user & Pass ... whatever unit has stronger signal a device (mobile,laptop etc) is locking automatic

I've got a 2710n - I have a long thin house with 2ft thick walls and the signal doesn't reach all areas. I've extended the WiFi range by using two old Netgear WG602 APs, but it only works if I don't use security. This isn't a huge issue for me as I live in a tiny hamlet and no one is likely to abuse my network! However, I'd like to have this work with security, and I'd also like all the APs to broadcast the same SSID and for any device to just connect to the strongest signal automatically.

The APs all need to be wireless - I don't have the option of cabling them.

Can I do this with the kit I have, or with another Draytek product?

As one further extension, I'd like to be able to get signal outdoors, which would require an outdoor AP - commercially, Cisco do a model, but I don't know if Draytek does?

sorry i don't have the netgear models to help ... i would say to post at netgear forums because they know its settings if is posible to do it wireless
Via wire as soon you connect a cable to the draytek it should extend the wifi range for the netgear or any other wifi router and work (assuming you have the correct setting of same keys and ssid) but as i said wireless i am not using the netgear to know its settings

A basic guide it to use the same wifi keys security ,ssid of the 2710 to the rest units, then try with dhcp on or off

At my post up i have a basic guide with one unit connected ap800 that works great without cable ... i am sure it is possible with 2 units (ap 800 because it has options in its manus for 1 or more connected) but you may need to enable dhcp

as for an outdoor unit i am not aware of any draytek model but you can use any unit if is under a roof for the rain don't damage it