Hi,

1)is DSL/T1/T3/E1/E3 are Layer 1? are the considered Leased Line?

T1/T3/E1/E3 can be considered as lease line but DSL can be considered as broadband.

http://en.wikipedia.org/wiki/Digital_Subscriber_Line   -- DSL Link

E1 Link:

E1 carries signals at 2 Mbps (32 channels at 64Kbps, with 2 channels reserved for signaling and controlling), versus the T1, which carries signals at 1.544 Mbps (24 channels at 64Kbps). E1 and T1 lines may be interconnected for international use.

T1 Link:

A dedicated phone connection supporting data rates of 1.544Mbits per second. A T-1 line actually consists of 24 individual channels each of which supports 64Kbits per second. Each 64Kbit/second channel can be configured to carry voice or data traffic. Most telephone companies allow you to buy just some of these individual channels, known as fractional T-1 access.

T-1 lines are a popular leased line option for businesses connecting to the internet and for ISP connecting to the Internet backbone.The Internet backbone itself consists of faster T-3 connections.

T-1 lines are sometimes referred to as DS1 lines.

T3 Link:

A dedicated phone connection supporting data rates of about 43 Mbps. A T-3 line actually consists of 672 individual channels, each of which supports 64 Kbps.T-3 lines are used mainly by Internet Service Providers (ISPs) connecting to the Internet backbone and for the backbone itself.
T-3 lines are sometimes referred to as DS3 lines.

Usually in L3 MPLS VPN, Ethernet link will be used.Either it may be fiber link or ethernet link

regards

karuppu