A Franco-Russo-Ethiopian Alliance

Would Ethiopia still be a ally of Russia even after the Russian Revolution.

Only IF there is no World War I to begin with, i do not see any reason why and how a Franco-Russo-Ethiopian Alliance could prevent that.

The French did make important investments, namely the Djibouti-Ethiopian railway, begun in 1897 and finished 1917. Started by a private company backed by British and French trusts, it ended under the firm control of the Djibouti colonial authority. The main thing is to avoid the 1906 treaty, which divided Ethiopia in three zones of influence : British, French and Italian. Will the Russian alliance be enough to keep Ethiopia out of the colonial projects (British North-South, French West-East) ?

Religiously speaking, the Christians of Ethiopia were members of the Coptic Church, meaning they are miaphysists no in communion with the "classic" Orthodox Church (the Egyptian Church in Communion with the Orthodoxs is the Greek Orthodox Church in Egypt). These religious differences are important in the Middle East and there were no religious talks between the Copts and the Greek Orthodoxs before the 1980'. So, for the Ethiopians, the Russians were heretics, little more than Nestorians.

1. Investing in one railroad is certainly nowhere near enough, though.

2. Possibly Yes.

Also, though, do you please have a link to this 1906 agreement?

3. Wouldn't Ethiopia have accepted any ally that it can get, though?

Here it is, its called the Tripartite Treaty (1906) between France, Italy, and the United Kingdom concerning Ethiopian sovereignty and railroad construction.

In assessing the events which brought Great Britain and France from the edge of war at Fashoda in 1898 to the alliance of 1914, scholars have paid little attention to the settlement of Anglo-French differences in the independent African empire of Ethiopia. The resolution of Ethiopian problems in 1906 was nonetheless important in forging close Anglo-French relations, especially when viewed within the context of the better-known Entente Cordiale of 1904. By excluding Anglo-French conflicting Ethiopian interests from the already difficult entente negotiations, British and French statesmen removed a potential stumbling block to that important and seminal agreement. In a more positive vein, the subsequent signing of a separate Tripartite Treaty on Ethiopia—the Italians were the third signatory—actively reinforced the Entente Cordiale itself. To the French the Ethiopian agreement was a confirmation of British good faith in implementing the spirit of the entente beyond areas specified in the more important accord of 1904. To the British it was an object lesson that certain imperial interests in Ethiopia should not jeopardize generally improving relations with France. To both countries the Tripartite Treaty of 1906 tidied unfinished business of the entente and eliminated to each nation's general satisfaction a nagging local conflict.
French Foreign Minister Theophile Delcassé had wanted to include Ethiopia in the entente agreement. During the course of the negotiations he suggested to his English counterpart Lord Lansdowne a “comprehensive settlement” of colonial-imperial differences. While individuals in the British Foreign Office considered adding Ethiopia to the larger rapprochement over Egypt and Morocco, the British cabinet decided to postpone Ethiopian matters until after conclusion of the Entente Cordiale. In good part this decision reflected respect for the complexity of strategic, financial, and personal rivalries of the two great imperial powers in Ethiopia and the Horn of Africa.

Well do not thank me, thank Google.

But i wonder would Ethiopia in World War I launch stacks against the Ottoman Empire as they are the only Central Powers member they can strike, unless Italy in this universe joins them.