Splines: vertex selection, tangents

Hello.
I have two problems I'm dealing with at the moment.

I have this open circle (I need this shape to be of open type) with start and end vertices stacked on each other (same world space coordinates). The thing is that MMB selection toggle doesn't always work here, so I cannot select the underlying vertex. I also need to correct their tangents, but MMB toggle doesn't work at all when "Tangent" tool is active. I tried a workaround, in which I moved one of those vertices away, modified its tangents and replaced it, but after the latter its tangents were reset.
Is there perhaps some way of iterating the selection through spline vertices? What I mean is that I press some key and the next spline vertex is selected. Like in Maya for example.

The second problem concerns "Joint Edges" tool. I have this spring shape which consists of several identical splines that are separate objects. I need to connect them all, but when I do this, all of their tangents get messed up. Is there any workaround to this?

I have this open circle (I need this shape to be of open type) with start and end vertices stacked on each other (same world space coordinates). The thing is that MMB selection toggle doesn't always work here, so I cannot select the underlying vertex.

When selecting the overlapping endpoints, the LMB selection will usually select the start vertex. Try changing the order(direction) of the spline so the start point of the spline is on the opposite end, and you should then be a able to select it. ("Geometry > Spline Commands n Tools > Reverse Order" or "Tool List > Spline Vertex Shortcut Tools > Reverse Order).

I also need to correct their tangents, but MMB toggle doesn't work at all when "Tangent" tool is active. I tried a workaround, in which I moved one of those vertices away, modified its tangents and replaced it, but after the latter its tangents were reset.

Use spline vertex > "Tweak". You can adjust vertex position with option "No auto naturalization". You can also adjust vertex tangency within spline_vertex_tweak mode.

The second problem concerns "Joint Edges" tool. I have this spring shape which consists of several identical splines that are separate objects. I need to connect them all, but when I do this, all of their tangents get messed up. Is there any workaround to this?

Why not create the spring(helix shape) from one spline?



Quick Helix:-

Create a 2 point spline, placing it at set distance from main axis (distance from axis = radius of Helix)



With spline selected. "Spline vertex > Lathe"
Set "Move per turn" for distance of helix for one turn.
Set number of turns.

Set "Generate Spline"



You can delete the created mesh, which will leave the spline Helix.



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When selecting the overlapping endpoints, the LMB selection will usually select the start vertex. Try changing the order(direction) of the spline so the start point of the spline is on the opposite end, and you should then be a able to select it. ("Geometry > Spline Commands n Tools > Reverse Order" or "Tool List > Spline Vertex Shortcut Tools > Reverse Order).

Use spline vertex > "Tweak". You can adjust vertex position with option "No auto naturalization". You can also adjust vertex tangency within spline_vertex_tweak mode.

Thank you Steve. Both of your tips work like a charm.

Why not create the spring(helix shape) from one spline?

Good question. I chose this way, because I thought it would be much quicker than manually laying down points and manipulating them into position. With plenty of coils in a helix, it can be a tedious process. Unless you're thinking of some other approach.
I didn't notice you edited your post. Oh yes, lathe looks like a much better solution. Why didn't I think of it in the first place?