Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,186
When you book an IB flight using IB+ Avios, you can usually select seats for free. And you receive a checked bag allowance.
For lounges, just show your AA card / phone app.
When you book an IB award flight using IB Avios, your IB+ number is usually too sticky to change. People might come along to offer workarounds that may or may not work (or stick for long), but as a self-confessed "newbie" I would just ignore all that.