1.3 Is there any limitation on the number of proposals that can be submitted by a same Lead Partner or partner under each Priority and Topic? Published 2011/05/26

Yes. According to paragraph 3.2.1 of the Guidelines for Applicants, one Organisation can choose to participate per each topic according to two different options:
1) ONCE as Applicant

Or

2) Twice as partner.

This means, for example, that if one University wants to submit a project as Applicant on the topic “solar energy”, it will be able to submit ONLY one project proposal without having the possibility to participate in other projects on “solar energy” as partner.