Well, there's the rub. We don't know what "structural design" means in this instance because the OP didn't describe the scope of the engineer's services. Since the structural elements of a single family house are normally described in great detail in the applicable building code, the structural engineer's services might consist of designing a complicated vertical and horizontal load transfer system in an earthquake or high wind zone or those services might consist of sizing a single LVL or steel beam. So many of the questions on the GardenWeb should be answered with "it depends on what you are talking about" rather than a long discussion based on a wide range of assumptions. If OP's want useful answers they need to describe the situations better IMHO. Start with the scope of structural work and the nature of the various contracts and then describe the engineer's fee and liability insurance as well as that of the Designer.

The lines to the room get hooked up to the punchdowns on the Cat5 voice/data module. If you look close they will have the numbers 1 through 6 next to each set of 8 colored connectors. After each of the 6 rooms is hooked up to this board, use the short grey jumpers to connect each each room from the voice/data module to the telephone distribution module. See page 9-6 in the link above.

Kidde and other smoke/CO detector manufacturers offer "relay boards" which connect to the interconnect and offer "dry contacts" - a relay switch that does not carry power - just an on/off switch - that can be connected to an alarm system. Note that in some places it's not code to connect these devices to an alarm system, so if you consider it, you should check. Alarm techs are also sometimes reluctant to use relay boards also, for a variety of reasons, but it is done, and it does work.

2008 NEC 250.130 Equipment Grounding Conductor Connections. Equipment grounding conductor connections at the source of separately derived systems shall be made in accordance with 250.30(A)(1). Equipment grounding conductor connections at service equipment shall be made as indicated in 250.130(A) or (B). For replacement of non– grounding-type receptacles with grounding-type receptacles and for branch-circuit extensions only in existing installations that do not have an equipment grounding conductor in the branch circuit, connections shall be equipment grounding conductor in the branch circuit, connections shall be permitted as indicated in 250.130(C) (C) Nongrounding Receptacle Replacement or Branch Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following: (1) Any accessible point on the grounding electrode system as described in 250.50 (2) Any accessible point on the grounding electrode conductor (3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates (4) For grounded systems, the grounded service conductor within the service equipment enclosure (5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure FPN: See 406.3(D) for the use of a ground-fault circuitinterrupting type of receptacle. 406.3 General Installation Requirements. Receptacle outlets shall be located in branch circuits in accordance with Part III of Article 210. General installation requirements shall be in accordance with 406.3(A) through (F). (D) Replacements. Replacement of receptacles shall comply with 406.3(D)(1), (D)(2), and (D)(3) as applicable. (1) Grounding-Type Receptacles. Where a grounding means exists in the receptacle enclosure or an equipment grounding conductor is installed in accordance with 250.130(C), grounding-type receptacles shall be used and shall be connected to the equipment grounding conductor in accordance with 406.3(C) or 250.130(C). (2) Ground-Fault Circuit Interrupters. Ground-fault circuit-interrupter protected receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code. (3) Non–Grounding-Type Receptacles. Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, the installation shall comply with (D)(3)(a), (D)(3)(b), or (D)(3)(c). (a) A non–grounding-type receptacle(s) shall be permitted to be replaced with another non–grounding-type receptacle(s). (b) A non–grounding-type receptacle(s) shall be permitted to be replaced with a ground-fault circuit interruptertype of receptacle(s). These receptacles shall be marked "No Equipment Ground." An equipment grounding conductor shall not be connected from the ground-fault circuitinterrupter-type receptacle to any outlet supplied from the ground-fault circuit-interrupter receptacle. (c) A non–grounding-type receptacle(s) shall be permitted to be replaced with a grounding-type receptacle(s) where supplied through a ground-fault circuit interrupter. Grounding-type receptacles supplied through the groundfault circuit interrupter shall be marked "GFCI Protected" and "No Equipment Ground." An equipment grounding conductor shall not be connected between the groundingtype receptacles.